TW202211287A - High throughput multi-beam charged particle inspection system with dynamic control - Google Patents

Abstract

A multi-beam charged particle inspection system and a method of operating a multi-beam charged particle inspection system for wafer inspection with high throughput and with high resolution and high reliability is provided. The method and the multi-beam charged particle beam inspection system are configured to extract from a plurality of sensor data a set of control signals to control the multi-beam charged particle beam inspection system and thereby maintain the imaging specifications including a movement of a wafer stage during the wafer inspection task.

Description

High-throughput multiple-beam charged particle detection system with dynamic control

The present invention relates to a multiple beam charged particle detection system and a method of operating the multiple beam charged particle detection system. In particular, the present invention relates to a multiple beam charged particle beam inspection system for wafer inspection with high throughput, high resolution and high reliability, and an associated method and a computer program product. The method and the multiple beam charged particle beam detection system are configured to extract a set of control signals from a plurality of sensor data to control the multiple beam charged particle beam detection system.

As smaller and more complex microstructures such as semiconductor devices continue to evolve, there is a need to further develop and optimize planar fabrication techniques, as well as inspection systems for the fabrication and inspection of small-scale microstructures. The development and manufacture of semiconductor devices requires, for example, design verification of test wafers, while planar manufacturing techniques involve process optimization for reliable high-throughput manufacturing. Additionally, there has recently been a need for analysis of semiconductor wafers for reverse engineering and customization and personalization of semiconductor devices. Therefore, there is a need for high-throughput inspection tools for testing on-wafer microstructures with high precision.

Typical silicon wafers used to manufacture semiconductor devices are up to 12 inches (300 mm) in diameter. Each wafer is divided into 30 to 60 repeating regions (“Dies”), with a maximum area of approximately 800 square millimeters. Semiconductors include multiple semiconductor structures fabricated in layers on the surface of a wafer by planar integration techniques. Due to the processes involved, semiconductor wafers typically have flat surfaces. The feature size of integrated semiconductor structures extends down to a critical dimension (CD) of 5 nm in the several µm range, and will even gradually decrease feature size in the near future, such as sub-3 nm (e.g. 2 nm) feature size or Critical dimension (CD), or even below 1 nm. With the aforementioned small feature sizes, critical dimension dimensional defects must be identified in a short time over a large area.

Accordingly, it is an object of the present invention to provide a charged particle system and a method of operating a charged particle system that allow high-throughput inspection of integrated semiconductor components with at least critical dimension resolution during development or manufacturing, or for use in semiconductor devices reverse engineering. It is also possible to capture a set of high-resolution images of specific locations on the wafer, for example only for so-called process control monitoring PCMs or critical areas.

The latest development in the field of charged particle microscopy CPM is MSEM, a multiple beam scanning electron microscope, such as disclosed in US Patent No. US20190355545 or US Patent No. US20190355544. In a multiple beam charged particle microscope, such as a multiple beam electron microscope or MSEM, the sample is irradiated by an array of electron sub-beams comprising, for example, 4 up to 10,000 electron beams (as primary radiation), with each electron beam being The beam is separated from its next adjacent electron beam by a distance of 1 - 200 microns. For example, an MSEM has about 100 separate electron beams or sub-beams arranged in a hexagonal array, where the electron sub-beams are separated by a distance of about 10 μm. A plurality of primary charged particle sub-beams are focused by a common objective lens on the surface of a sample under study, such as a semiconductor wafer held on a wafer chuck, which is mounted on a movable stage. During irradiation of the wafer surface with a beam of primary charged particle beams, interaction products, such as secondary electrons, originate from multiple intersections formed by the focal point of the beam of primary charged particles, and the number and energy of the interaction products depend on The material composition and morphology of the wafer surface. The interaction products form a plurality of secondary charged particle sub-beams, which are collected by a common objective and directed onto detectors disposed on the detector plane by the projection imaging system of the multiple beam detection system. The detector includes a plurality of detection regions, each region includes a plurality of detection pixels, and detects the intensity distribution of each of the plurality of secondary charged particle sub-beams, and obtains, for example, 100 µm × 100 µm Image patches.

Prior art multiple beam charged particle microscopes include a series of electrostatic and magnetic elements. At least some of the electrostatic and magnetic elements are adjustable to adjust the focal position and astigmatism of the plurality of secondary charged particle beams. For example, US Patent No. 10535494 proposes to readjust the charged particle microscope if the focal intensity distribution of the detected secondary charged particle beamlets deviates from a predetermined intensity distribution. An adjustment is achieved if the detected intensity distribution conforms to the predetermined intensity distribution. Global displacement or deformation of the intensity distribution of the secondary charged particle sub-beam allows conclusions to be drawn about topographic effects, sample geometry or tilt, or sample charging effects. US Patent No. 9,336,982 discloses a secondary charged particle detector with a scintillator plate that converts secondary charged particles into light. In order to reduce the loss of conversion efficiency of the scintillator plate, the relative lateral position of the focal points of the plurality of secondary charged particle beamlets to the scintillator plate can be varied, for example by a charged particle beam deflector or induction for lateral displacement of the scintillator plate. actuator.

Prior art multiple beam charged particle microscopes include at least one intersecting plane of primary or secondary charged particle sub-beams, and prior art multiple beam charged particle microscopes include easily adjustable detection systems and methods.

It is often desirable to change the imaging settings of a charged particle microscope. US Patent No. 9,799,485 discloses a method of changing the image capture setting of a multiple beam charged particle microscope from a first imaging setting to a second, different imaging setting.

However, in charged particle microscopes for wafer inspection, it is desirable to keep imaging conditions stable so that imaging can be performed with high reliability and repeatability. The flux depends on several parameters, such as the speed of the stage and the realignment of the new measurement point, as well as the measurement area per acquisition time itself, which is determined by dwell time, resolution and number of beamlets. Between capturing two image patches, the wafer is moved laterally from the wafer stage to the next relevant point. Stage movement and precise alignment of the next position for image capture is one of the limiting factors for the throughput of multi-beam detection systems. During high-throughput image acquisition, unwanted stage movement or drift can degrade image resolution. During high-throughput image acquisition, drift and deviation of the predetermined primary and secondary charged particle beam paths have a negative impact on image quality and reliability of measurement results. For example, the plurality of primary charged particle sub-beams may deteriorate from the grating configuration within the planar area segment, or the resolution of the multiple beam charged particle detection system may change.

Single-beam electron microscopes typically use a so-called beam error function (BEF) to improve the positioning accuracy of the electron beam as well as stage movement. For this purpose, the BEF feeds back the (position) signal from the stage that fixes the sample to the beam deflection system. A recent example is given in patent case WO2020/136094 A2. However, multiple beam charged particle microscopy is more complex and the simple methods of single beam electron microscopy are not sufficient. For example, the prior art cannot compensate for the rotation of the focal points of the primary charged particle beamlets relative to the wafer stage. Furthermore, multiple beam charged particle microscopes have an imaging projection system for imaging a plurality of secondary electron sub-beams onto a detector and must maintain accurate imaging of the plurality of secondary electrons. In addition, the aberrations of the secondary beam path must be separated and taken into account.

US Patent No. US9530613 discloses a focus control method of a multiple beam charged particle microscope. Subsets of the plurality of charged particle beamlets are shaped as astigmatism and used to detect deviations in focus position. An error signal is generated based on the corresponding elliptical shape of the astigmatic shaped sub-beams and adjusts the vertical position of the sample stage or changes the current through one or more lenses in the charged particle microscope. Thereby, the focal points of the plurality of charged particle sub-beams are optimized. The method operates in parallel with the normal operation of a scanning electron microscope. However, this approach only provides a feedback loop for focus control and neither provides predictive control nor takes into account the sensor signal from the stage position sensor.

US patent applications US20190355544 or US20190355545 disclose a multiple beam charged particle microscope with an adjustable projection system to compensate for the charging of the sample during scanning. Therefore, the projection system is configured with fast electrostatic elements to maintain proper imaging of the secondary charged particle beamlets from the sample to the detector. Both references use an image detector to analyze the imaging quality of the secondary electron beam and compensate for degradation due to sample charging in the secondary electron beam path. Both references describe methods and apparatus for controlling the path of a secondary electron beam, starting from the surface of the sample. However, the problem with the present invention is that there is also a source of error within the primary beam path, which is responsible for the deterioration of the spot position and spot shape of the plurality of primary charged particle sub-beams on the surface of the substrate. Furthermore, additional error sources may be positioning errors or movement of the substrate stage, resulting in aberrations in the obtained digital image of the object without any main beam path degradation. These additional aberrations and errors may vary over different time scales, such as slowly varying drift, eg due to thermal drift. Another example is rapidly changing dynamic aberrations, eg due to sound vibrations. These errors cannot be compensated by auxiliary beam paths alone. The problem of the present invention is to provide a multiple beam charged particle detection system, which has a device capable of realizing high-precision and high-resolution image capture with high throughput and high reliability. The problem of the present invention is to provide a multiple beam charged particle detection system with a fast stage, which has the ability to maintain the lateral position and focus of a plurality of primary charged particle sub-beams within a predetermined positional accuracy within a predetermined grating configuration, even if Reduce time for precise stage alignment. It is a problem of the present invention to provide a multiple beam charged particle detection system with high throughput and high reliability in image patch order, maintaining high resolution and high image contrast during image capture. One problem of the present invention is to provide a multiple beam charged particle detection system with high throughput and high reliability, with a stage for moving wafers from a first inspection point to a second inspection point. It is a problem of the present invention to provide a multiple beam charged particle detection system with means to compensate for drift in predetermined primary and secondary charged particle beam paths and for stage movement, eg parasitic stage movement.

Stage movement, such as stage acceleration, deceleration, and ringing, is one of the limiting factors for the throughput of multiple beam detection systems. Accelerating and decelerating a stage in a short period of time often requires a complex and expensive stage. The problem of the present invention is to provide a multi-beam charged particle detection system, which has a stage capable of achieving high-throughput and high-reliability, high-precision and high-resolution image capture with a stage that reduces technical complexity and cost. device.

In general, it would be desirable to provide a multiple beam charged particle inspection system for wafer inspection with high throughput and high reliability for devices that enable high precision and high resolution image capture.

Embodiments of the present invention address the objects of the present invention by a multiple beam charged particle microscope comprising a set of compensators for compensating for variations in error amplitude during image acquisition of image patches. The multiple beam charged particle microscope includes a plurality of detectors or sensors to provide a plurality of sensor data and extract a set of actual errors from a set of predefined normalized error vectors from the plurality of sensor data amplitude. Contributions from different error sources can be separated by deriving a normalized error vector. Different sources of error include error sources on the primary charged particle beam path, on the secondary electron beam path, and within the stage position. The multiple beam charged particle microscope includes a control unit that derives a drive signal for driving the set of compensators to compensate for a set of error amplitudes corresponding to a set of imaging aberrations so that during image acquisition of the digital image of the imaging plaque , keeping the actual error amplitude below a predetermined threshold. From normalized error vectors representing contributions from different error sources, the drive signals for a set of compensators are derived, including a first compensator in the path of the primary charged particle beam and a second compensator in the path of the secondary electron beam at least one of them. Another compensator may include computational image post-processing of the acquired digital image, or a compensator within the wafer stage.

In one example, the multiple beam charged particle microscope is configured to predict changes in at least one error amplitude of the set of error amplitudes, and provide corresponding drive signals to the set of compensators accordingly. In one example, the plurality of sensor data includes data from a stage position sensor or a stage acceleration sensor. In one example, the set of compensators includes first and second deflection systems or deflection scanners of a multiple beam charged particle microscope. In another example, the set of compensators includes a third deflection system within the detection unit of the multiple beam charged particle microscope. In one example, the set of compensators further includes at least one fast electrostatic compensator or one multi-aperture active array element.

According to specific embodiments of the present invention, the multiple beam charged particle detection system is equipped with devices that achieve high-precision and high-resolution image capture with high throughput and high reliability. A wafer stage and means for controlling the position of the wafer stage are provided, wherein the wafer stage is configured to hold a sample, such as a wafer, and is movable in at least one of an x-direction, a y-direction, or a z-direction. The carrier typically includes a carrier motion controller that includes a plurality of motors or actuators that can be actuated or controlled independently. The motor or actuator may include at least one of a piezoelectric motor, a piezoelectric actuator, or an ultrasonic piezoelectric motor. It further includes a position sensing system configured to determine lateral and vertical displacement or rotation of the stage using any of laser interferometers, capacitive sensors, confocal sensor arrays, grating interferometers, or combinations thereof. one.

The multiple beam charged particle detection system is configured with means for maintaining the focal points of the plurality of primary charged particle beamlets at a lateral position on the wafer surface, and means for maintaining the lateral positions of the focal points of the plurality of secondary electron beamlets, Each beamlet is within a predetermined raster configuration, and each beamlet is within a predefined positional accuracy below a set of thresholds. Thus, in one example, shortening the time for precise stage alignment is achieved. In another example, throughput is further increased by overlapping the time interval required for image capture and wafer stage movement. The additional device includes a first deflection unit for scanning deflections of a plurality of primary charged particle beamlets, and at least a second deflection unit for scanning deflections of a plurality of secondary electron beamlets.

According to an embodiment of the present invention, a multiple beam charged particle detection system is configured with high throughput and high reliability in image patch order, maintaining high resolution and high image contrast during image capture. During the first and second image capture, a plurality of sensor data is generated, including sensor data from the image sensor and the stage position sensor. The multiple beam charged particle detection system includes a control unit configured to generate a set of control signals from the plurality of sensor data. The group of control signals is configured as a control module to control a group of compensators. According to specific embodiments of the present invention, a multiple beam charged particle detection system is provided with means to compensate for predetermined primary and secondary charged particle beam path drift and stage movement.

According to one example, a multiple beam charged particle beam system includes a controller or control unit configured to apply a first signal to deflect a plurality of primary charged particle beams incident on a sample to at least partially compensate for lateral displacement of the stage and applying a second signal to deflect the plurality of secondary electron sub-beams to at least partially compensate for displacement of the plurality of secondary electron sub-beams originating from the positions on the sample where the primary charged particle sub-beams have been deflected. The first signal includes an electrical signal that affects how the plurality of primary charged particle beamlets are deflected in at least one of the X-axis or the Y-axis. The controller is further configured to dynamically adjust at least one of the first signal or the second signal during scanning of the plurality of primary charged particle sub-beams on the sample. The controller is connected to the stage motion controller, and each of the plurality of motors is independently controlled to adjust the tilt of the stage so that the stage is substantially perpendicular to the optical axis of the primary charged particle beam. According to an embodiment of the present invention, a multiple beam charged particle microscope system includes a charged particle source configured to generate a first charged particle beam during use; and a multiple beam generator configured to generate, during use, a beam from a plurality of primary charged particle sub-beams of the incident first charged particle beam, wherein each individual sub-beam of the plurality of primary charged particle sub-beams and all other sub-beams of the plurality of charged particle sub-beams are in the Spatially separated. The multiple beam charged particle microscope system further includes an object illumination unit including an objective lens configured to impinge on a first one in the object plane with a first individual primary beamlet of the plurality of charged particle beamlets The manner in which the image subfield is spatially separated from the second image subfield in which a second individual primary beamlet of the plurality of primary charged particle beamlets impinges on the object plane, focusing the incident primary charged particle beamlet on the object plane that provides the wafer surface. The multiple beam charged particle microscope system further includes a detection unit including a projection system and an image sensor including a plurality of individual detectors. The projection system is configured to image the secondary electrons exiting the wafer in a first image subfield within the object plane as the primary charged particles impinge on a first one or a first group of the plurality of individual detectors, And since the primary charged particles impinge on the second or second set of the plurality of individual detectors, the projection system is configured to image the secondary electrons exiting the wafer in a second imaging subfield within the object plane.

In a specific embodiment of the multiple beam charged particle microscope system, it includes a subset of fast compensators that provide fast compensation of error amplitude dynamic changes. A subset of fast compensators include at least one of electrostatic lenses, electrostatic deflectors, electrostatic astigmatists, electrostatic microlens arrays, electrostatic astigmatism arrays, or electrostatic deflector arrays. Electrostatic components, such as electrostatic deflectors and/or electrostatic astigmatism, are eddy-current free, non-inductive, and provide settling times in the sub-10 µs range to compensate for dynamic changes in error amplitude.

Subcomponents that provide fast compensation for dynamic changes can provide an adjustment frequency equivalent to the scanning frequency of the charged particle sub-beam scanning once, i.e. fast compensation for dynamic changes can be performed multiple times, ie more than once, while the image patches on the wafer surface are swept away. Image acquisition is performed using a plurality of primary charged particle beamlets. Typical line scan frequencies are on the order of 1 kHz to 5 kHz, and the electrical drive signal of the dynamic compensation element can have a bandwidth in the range of 0.1 kHz to 10 kHz, providing for example between 10 times per 50 scan lines or 10 times per scan line. compensate.

In a specific embodiment of a multiple beam charged particle microscope system, it includes a subset of slow acting compensators that provide compensation for slow changes or drifts in error amplitude. A subset of slow-acting compensators include at least one of a magnetic lens, a magnetic deflector, a magnetic astigmatism, or a magnetic beam splitter.

In a specific embodiment, a multiple beam charged particle microscope for wafer inspection is provided. A multiple beam charged particle microscope for wafer inspection includes a charged particle multiple beam generator for generating a plurality of primary charged particle beamlets, and a first deflection system to scan using the plurality of primary charged particle beamlets The object irradiation unit is arranged in the wafer surface area in the object plane to generate a plurality of secondary electron sub-beams emitted from the wafer surface. The multi-beam charged particle microscope for wafer inspection further includes a detection unit having a projection system, a second deflection system and an image sensor for imaging a plurality of secondary electron beams onto the image sensor on the wafer surface, and captures a digital image of the first image patch on the wafer surface during use. The multiple beam charged particle microscope for wafer inspection further includes a sample stage with a stage position sensor for positioning and maintaining the wafer surface at the object plane during acquisition of the digital image of the first image patch middle. While the wafer is being held by the wafer stage, the first deflection system scans a plurality of primary charged particle beamlets along a predetermined scan path on the wafer surface, and the second deflection unit scans a plurality of secondary electron beams along the predetermined scan path sub-beams, so as to keep the image points of the plurality of secondary electron sub-beams fixed at the image sensor of the detection unit. The multiple beam charged particle microscope for wafer inspection further includes a control unit and a plurality of detectors including a stage position sensor and the image sensor configured to generate a plurality of detectors during use A sensor data that includes the following sample stage position and orientation data. The multiple beam charged particle microscope for wafer inspection further includes a set of compensators, the set of compensators including at least first and second deflection systems. The control unit is configured to generate a set of P control signals _Cp from the plurality of sensor data to control the set of compensators during the capture of the digital image of the first image patch. The set of compensators may further include at least one of a compensator of the charged particle multiple sub-beam generator and a compensator of the detection unit. In one example, the control unit includes a sensor data analysis system configured to analyze a plurality of sensor data during use and to calculate a set of K amplitudes _Ak of the K error vectors during use. In one embodiment, the control unit further includes an image data capture unit configured to reduce the image sensor data from the image sensor during use to less than 10% of the image sensor data, preferably less than 2% of the image sensor data portion, and provide the image sensor data portion to the sensor data analysis system. In one example, the image sensor data portion includes digital image data of a plurality of secondary electron beamlets at a reduced sampling rate. In one example, the image sensor data portion includes digital image data that reduces the secondary electron beamlet set (9).

In one example, the sensor data analysis system is further configured to derive or predict the temporal development of at least one amplitude An within the set of amplitudes _Ak in the error _vector .

In an example, the control unit further includes a control arithmetic processor for calculating the set of control signals C _p according to the set of amplitudes A _k of the error vectors. In one example, the acquisition of at least one of the plurality or set of control signals is further based on a predictive model of the actuation output of the stage.

In one example, the sensor data analysis system is configured to derive a sensor data vector DV of length L, where L >= K, from a plurality of sensor data.

In one example, the control unit is configured to compensate for changes in the position or orientation of the sample stage by calculating and providing at least one control signal of the first set of control signals _Cp to the first and second deflection units. The change in position or orientation of the sample stage is imparted by the lateral displacement of the stage, corresponding to the difference in at least one of the XY axes between the current position and rotation of the stage and the target position and rotation of the stage.

The control unit is configured to derive a drive signal for a first compensator in the object irradiation unit from the plurality of sensor data, so as to achieve a difference between the scanning spot positions of the plurality of primary charged particle beamlets The additional displacement is synchronized with the lateral displacement of the wafer surface. In one example, the additional displacement includes a plurality of grating configuration rotations of the primary charged particle beamlets. The control unit is further configured to compensate for additional displacement of the spot position on the displaced wafer surface via a second compensator in the projection system, wherein the second compensator in the projection system is configured to be compatible with the first compensator in the object illumination unit Synchronous operation, so that the spot positions of the plurality of secondary electron sub-beams on the image detector remain constant. In one example, the first compensator in the object illumination unit is a first deflection system, and the control unit is configured to calculate and use for control of additional displacement or rotation of the scanning spot positions of the plurality of primary charged particle sub-beams Signals are provided to the first deflection system to compensate for displacement or rotation of the sample stage. In one example, the second compensator projection system is a second deflection system, and the control unit is configured to compensate the scanning spot positions of the plurality of primary charged particle beamlets by calculating and providing control signals to the second deflection system. Additional displacement or rotation on the displaced wafer surface. Thus, the spot position of the secondary electron sub-beam remains constant at the image sensor regardless of the scan path modified according to the displacement or movement of the wafer stage.

In a specific embodiment, the charged particle multiple beam sub-beam generator of the multiple beam charged particle microscope further includes a fast compensator, and the control unit is configured to calculate and provide at least one of the control signals of the first set of control signals C _p . One gives a fast compensator to cause rotation of a plurality of primary charged particle beamlets to compensate for rotation of the sample stage. In one embodiment, the control unit of the multiple beam charged particle microscope is further configured to generate a third control signal for moving the wafer surface through the wafer stage to a second center position of the second image patch in the object plane, Image capture of the digital image of the second image patch is performed. In a specific embodiment, the control unit is further configured to calculate a second set of P control signals C _p from the data of the plurality of sensors for the time interval Tr when the wafer stage moves to the second center position of the second image patch During this time, the group of compensators are controlled. In a specific embodiment, the control unit is further configured to calculate the image capture start time of the second image patch during the time interval Tr, and to start the image capture of the second image patch during the deceleration time interval Td of the wafer stage. and wherein the control unit is further configured to provide the first and second deflection yokes with an offset signal at least one of the predicted offset positions of the wafer stage during the time interval Td.

In one embodiment, a method of inspecting a wafer using a multiple beam charged particle microscope is provided. The multiple beam charged particle microscope of the method includes a plurality of detectors, the detectors including an image sensor and a stage position sensor; and a set of compensators, the set of compensators including at least a first and the second deflection yoke. The method includes the following steps: a. Using the line of sight of the multiple beam charged particle microscope, locate the wafer surface of the wafer and align with the location of the local wafer coordinate system; b. Perform an image capture to capture the a digital image of the first image patch on the wafer surface; c. collecting a plurality of sensor data from the plurality of detectors during the image capture step; d. deriving from the plurality of sensor data derive a set of K error amplitudes _Ak ; and e. derive a set of P control signals _Cp from the set of error amplitudes _Ak ; f. provide the set of control signals _Cp during step b of image capture to a set of compensators.

In a specific embodiment, the wafer inspection method further includes the step (g) of deriving a sensor data vector DV of length L from the plurality of sensor data, where L >=K. In one embodiment, the wafer inspection method further includes the step (h) of deriving the time development of at least one amplitude An in the set of error _vector amplitudes _Ak . In a specific embodiment, the wafer inspection method further includes the step (i) of compensating for changes in the position or orientation of the sample stage by providing a control signal C _p to the first and second deflection units. In a specific embodiment, the wafer inspection method further includes deriving a second set of control signals _Cp from the set of error amplitudes _Ak , and in the step (a) of locating and aligning the wafer surface of the wafer During the step (j) of providing the second group of control signals.

In one embodiment of the present invention, a charged particle microscope and a method of operating a charged particle microscope at high throughput and high resolution according to the imaging specification requirements of wafer inspection tasks are provided, wherein a series of image patches are The image capturing step is sequential imaging, which includes a first image capturing of a first image patch in a first time interval Ts1 and a second image capturing of a second image patch in a second time interval Ts2, and It further includes a third time interval Tr for moving a sample stage from the first center position of the first image patch to the second center position of the second image patch, so that the first and second time At least one of the intervals Ts1 or Ts2 has an overlap with the third time interval Tr. The total time interval from the start of the first time interval Ts1 to the end of the second time interval Ts2 is less than the sum of the three time intervals Ts1 , Tr and Ts2 , and high-throughput fast wafer inspection is achieved. In one example, before the end of the third time interval Tr, ie, before the sample stage has come to a complete stop, the second image capture of the second image patch is started. In an example, when the third time interval Tr of the sample movement is started before the end of the time interval Ts1, that is, before the image capture of the first image patch is completed. In an example of the method, the calculation of the start time of the third time interval Tr of the sample movement is performed during the first time interval Ts1 of the image capture of the first image patch such that the first center of the first image patch The positional deviation from the line of sight of the multiple beam charged particle microscope or the moving speed of the sample stage is below a predetermined threshold. In an example of the method, the calculation of the start time of the second time interval Ts2 of the second image capture is performed during the time interval Tr of the movement of the sample stage, so that the second center position of the second image patch and the multiple The positional deviation of the beam charged particle microscope sight line or the moving speed of the sample stage is below a predetermined threshold.

In an exemplary method of operating a multiple beam charged particle microscope, the method includes the following further steps: predicting the sequence of sample stage positions during the time interval Tr of the wafer stage movement; calculating at least first and second control signals based on the predicted sample stage position; The first control signal is provided to a first deflection system in the primary beam path of the multiple beam charged particle microscope, and the second control signal is provided to a second deflection system in the secondary beam path.

In one example, the charged particle microscope includes a control unit configured to calculate the movement of the sample stage from the first image patch to the second image patch during a first image acquisition of the first image patch start time. In an example of the present invention, the charged particle microscope includes a control unit configured to calculate the period during which the sample stage moves from the first image patch to the second image patch, and to capture the first image of the second image patch. 2. The start time of the image.

In a specific embodiment, a method of operating a multiple beam charged particle microscope configured for wafer inspection is described that includes the following preparatory steps: define a set of image qualities and a set of predetermined, normalized error vectors describing deviations from the set of image qualities; determine a set of thresholds for the amplitude of the set or normalized error vector; Select a set of compensators for multiple beam charged particle microscopes; determining a sensitivity matrix by varying at least one drive signal of each compensator in the set of compensators according to a linear and/or nonlinear perturbation model; deriving a set of normalized drive signals for compensating each of the set of normalized error vectors; and The normalized drive signals and the set of thresholds are stored in the memory of the control unit of the multiple beam charged particle microscope.

In one example, the set of compensators includes a first deflection unit of the multiple beam charged particle microscope for scanning and deflecting a plurality of primary charged particles, and for scanning and deflecting the multiple beam charged particle microscope during use of the multiple beam charged particle microscope The second deflection unit of the generated secondary electrons.

This sensitivity matrix is analyzed, for example, by singular value decomposition or similar algorithms. In one example, the sensitivity matrix is decomposed by dividing into two, three or more kernels or independent subsets of image quality. This reduces computational complexity and reduces nonlinear or higher-order effects.

During use, such as during wafer inspection, the method of operation includes using the normalized error vector, normalized drive signal and the set of thresholds stored in the control unit memory of the multiple beam charged particle microscope. A method of operating a multiple beam charged particle microscope comprising: the step of receiving a plurality of sensor data from a plurality of sensors of the multiple beam charged particle microscope during use to form a sensor data vector; the step of expanding the sensor data vector within a set of normalized error vectors stored in control unit memory, and determining the actual amplitude of a set of normalized error vectors from the sensor data vector; a step of comparing the set of actual amplitudes with a set of thresholds stored in the control unit memory, and according to the comparison result; the step of deriving a set of control signals from the set of actual amplitudes; The step of deriving a set of actual drive signals from a set of normalized drive signals stored in the control unit memory from the set of control signals; the step of providing the set of actual drive signals to a set of compensators in the multiple beam charged particle microscope to keep the set of actual amplitudes of the set of normalized error vectors below the multiple beam charged particle microscope during operation of the multiple beam charged particle microscope group critical.

In one example, the plurality of sensor data includes at least one of position or velocity information for maintaining actual wafer stage position and actual velocity of the wafer during inspection using multiple beam charged particle microscopy. The set of actual amplitudes from the normalized error vector of the sensor data vector represents the actual state of the image quality set of the multiple beam charged particle microscope. A set of control signals is derived by comparison with predetermined and stored thresholds. From the control signal, a set of actual drive signals is calculated, eg by multiplying the control signal by a predetermined set of normalized drive signals. During image scanning or image acquisition of at least one image patch, the set of actual drive signals is provided to the set of compensators to reduce the subset of actual amplitudes to below A predetermined critical subset is stored in the control unit memory. The method steps are repeated at least twice, at least ten times, preferably for each scan line, during the capture of each image patch.

In one example, the method further includes the step of predicting a subset of developed amplitudes of at least a subset of the set of actual amplitudes based on expected development of the multiple beam charged particle microscope over a predicted time interval during wafer inspection. The method may further comprise the step of recording at least a subset of the set of actual amplitudes of the multiple beam charged particle microscope during use for generating the subset history of the set of actual amplitudes. The method of operation of the multiple beam charged particle microscope further includes the steps of deriving a set of predictive control signals from the set of developmental amplitudes and deriving a set of predictive drive signals from the set of predictive control signals during wafer inspection, and The step of providing the set of predicted drive signals to the set of compensators in a time-sequential manner during detection to reduce the subset of actual amplitudes below the set of compensators during operation of the multiple beam charged particle microscope over the predicted time interval group critical.

The expected development of the multiple beam charged particle microscope over the predicted time interval is determined from a predictive model function or one of a set of linear, second- or higher-order extrapolations of the actual amplitude history. In one example, the method may further include the step of recording at least a subset of the set of actual amplitudes of the multiple beam charged particle microscope during use for generating the subset history of the set of actual amplitudes. The method further includes the steps of deriving a set of predicted control signals from the set of developmental amplitudes and deriving a set of predicted drive signals from the set of predicted control signals during wafer inspection, and in a time-sequential manner during wafer inspection The step of providing the set of predicted drive signals to the set of compensators reduces a subset of the actual amplitudes below the set of thresholds during operation of the multiple beam charged particle microscope within the predicted time interval. This particular embodiment includes a multiple beam charged particle microscope configured to apply the aforementioned method steps during use.

In various embodiments, the error amplitudes derived from sensor data represent image performance specifications for wafer inspection tasks, such as the line of sight of the wafer stage relative to the multiple beam charged particle microscope and the multiple beam charged particle microscope at least one of the relative position and orientation of the image coordinate system, the magnification or spacing of the multiple-beam charged particle microscope, the telecentricity condition, the contrast condition, the absolute positional accuracy of the plurality of charged particle beamlets, and higher-order aberrations such as Distortion, astigmatism and chromatic aberration of a plurality of charged particle beamlets.

In one embodiment, a multiple beam charged particle microscope and software code are disclosed. The multiple beam charged particle microscope includes a set of compensators including a plurality of deflectors, a control unit and installed software code configured for applying any of the methods according to the preceding method steps.

In one embodiment, a non-transitory computer-readable medium is disclosed that includes a set of instructions executable by one or more processors of a multiple beam charged particle device to cause the device to perform a method , wherein the device includes a charged particle source to generate a plurality of primary charged particle beamlets, and the method includes: determining the lateral displacement of the stage, wherein the stage is movable in at least one of the X-Y axes; and The controller is instructed to apply a first signal to deflect the plurality of primary charged particle beamlets incident on the sample to at least partially compensate for the lateral displacement. In one example, the set of instructions includes execution of a method including instructing the controller to apply a second signal to deflect a plurality of secondary electron beamlets emitted from the sample to at least partially compensate for lateral displacement of the sample stage.

In the exemplary embodiments described below, functionally and structurally similar components are denoted by similar or identical reference numerals wherever possible.

1 is a schematic diagram showing the basic features and functions of a multiple sub-beam charged particle microscope system 1 according to an embodiment of the present invention. It is noted that the symbols used in the figures do not represent the physical configuration of the illustrated components, but have been chosen to symbolize their respective functions. The type of system shown is a Scanning Electron Microscope (SEM) that uses a plurality of primary electron beamlets 3 to generate a plurality of primary charged particles on the surface of an object 7, such as a wafer located in the object plane 101 of the objective 102 Beam spot 5. For simplicity, only five primary charged particle sub-beams 3 and five primary charged particle beam spots 5 are shown. Electrons or other types of primary charged particles (eg ions, especially helium ions) may be used to achieve the properties and functionality of the multiple sub-beam charged particle microscope system 1 .

The microscope system 1 includes an object irradiation unit 100 and a detection unit 200 , and a beam splitter unit 400 for separating the secondary charged particle beam path 11 from the primary charged particle beam path 13 . The object irradiation unit 100 comprises a charged particle multiple beamlet generator 300 for generating a plurality of primary charged particle beamlets 3 and adapted to focus the plurality of primary charged particle beamlets 3 in the object plane 101, wherein the wafer 7 The surface 25 is positioned by the sample stage 500 . The sample stage 500 includes a stage motion controller, wherein the stage motion controller includes a plurality of motors configured to be independently controlled by control signals. The stage motion controller is connected to the control unit 800 .

The primary sub-beam generator 300 generates a plurality of primary charged particle sub-beam spots 311 in an intermediate image plane 321 , which is typically a spherically curved surface, to compensate for the field curvature of the object illumination unit 100 . The primary beamlet generator 300 includes a source 301 of primary charged particles (eg, electrons). For example primary charged particle source 301 emits a diverging primary charged particle beam 309, which is collimated by collimating lenses 303.1 and 303.2 to form a collimated beam. Collimating lenses 303.1 and 303.2 typically consist of one or more electrostatic or magnetic lenses, or a combination of electrostatic and magnetic lenses. The collimated primary charged particle beam is incident on the primary multiple sub-beam forming unit 305 . The multiple sub-beam forming unit 305 basically comprises a first multiple aperture plate 306 . 1 irradiated by the primary charged particle beam 309 . The first multiple aperture plate 306.1 comprises a plurality of apertures in a grating configuration for generating a plurality of primary charged particle beamlets 3 which are transmitted through the plurality of apertures by a collimated primary charged particle beam 309. produce. The multiple sub-beam forming unit 305 comprises at least a further multiple aperture plate 306.2 which is located downstream of the first multiple aperture plate 306.1 with respect to the direction of movement of the electrons in the electron beam 309. For example, the second multi-well plate 306.2 has the function of a microlens array and is preferably set to a defined potential to adjust the focus position of the plurality of primary beamlets 3 in the intermediate image plane 321. A third active multi-well plate configuration 306.3 (not shown) includes individual electrostatic elements for each of the plurality of wells to individually affect each of the plurality of beamlets. Active multi-well plate configuration 306.3 consists of one or more multi-well plates with electrostatic elements, such as circular electrodes for microlenses, multipole electrodes or a series of multipole electrodes to form a deflector array, microlens array or Column head array. The multiple beamlet forming unit 305 consists of the adjacent first electrostatic field lens 307 and, together with the second field lens 308 and the second multiple aperture plate 306.2, focuses the plurality of primary charged particle beamlets 3 at the intermediate image plane In or near 321.

In or near the intermediate image plane 321, a beam steering multi-aperture plate 390 is configured with a plurality of apertures with electrostatic elements (eg, deflectors) to steer each of the plurality of charged particle beamlets 3, respectively By. The aperture of the beam-steering multi-orifice plate 390 is configured to have a larger diameter to allow the passage of a plurality of primary charged particle beamlets 3, even if the focal point of the primary charged particle beamlets 3 is deviated from its design position. pass.

The foci of the primary charged particle sub-beam 3 passing through the intermediate image plane 321 are imaged in the image plane 101 by the field lens groups 103.1 and 103.2 and the objective lens 102, wherein the surface to be investigated of the wafer 7 is captured by the sample stage 500. object holder positioning. The object illumination system 100 further includes a deflection system 110 near the first beam intersection 108, so that the plurality of charged particle beamlets 3 can be deflected in a direction perpendicular to the beam propagation direction (here, the z-direction). The deflection yoke 110 has been connected to the control unit 800 . Objective 102 and deflection system 110 are centered on optical axis 105 of multiple beamlet charged particle microscope system 1 perpendicular to wafer surface 25 . The wafer surface 25 disposed in the image plane 101 is then raster scanned with the deflection yoke 110 . Thus, a plurality of primary charged particle beamlets 3 of a plurality of beam spots 5 in a grating configuration are formed by synchronous scanning on the wafer surface 101 . In one example, the grating of the focal points 5 of the primary charged particle beams 3 is configured as a hexagonal grating of about one hundred or more primary charged particle beamlets 3 . The primary beam spot 5 has a distance of about 6 μm to 15 μm and a diameter of less than 5 nm, eg 3 nm, 2 nm or even smaller. In one example, the beam spot size is about 1.5 nm, and the distance between two adjacent beam spots is 8 µm. At each scanning position of each of the plurality of primary beam spots 5 , a plurality of secondary electrons are respectively generated to form a plurality of secondary electron sub-beams 9 in the same grating configuration as the primary beam spot 5 . The number or intensity of secondary charged particles generated at each beam spot 5 depends on the intensity of the impinging primary charged particle sub-beam, the illumination of the corresponding spot, the material composition and topography of the object under the beam spot. The secondary charged particle sub-beam 9 is accelerated by the electrostatic field generated by the sample charging unit 503 , collected by the objective lens 102 , and guided to the detection unit 200 by the beam splitter 400 . The detection unit 200 images the secondary electron beam 9 onto the image sensor 207 to form a plurality of secondary charged particle image spots 15 therein. The detector includes a plurality of detector pixels or individual detectors. For each of the plurality of secondary charged particle beam spots 15, the intensity is detected separately, and the material composition of the wafer surface is detected at high resolution with high throughput for large image patches. For example, for a 10x10 beamlet grating with 8 µm pitch, one image scan with deflection yoke 110, with an image resolution of eg 2 nm, produces an image patch of approximately 88 µm x 88 µm. Image patches are sampled at half the beam spot size, e.g. 2 nm, so for each sub-beam, the number of pixels per image row is 8000 pixels, so that the image patch produced by 100 sub-beams includes 6.4 billion pixel. The control unit 800 collects image data. Details of digital image data collection and processing using eg parallel processing are described in German Patent Application 102019000470.1, which is hereby incorporated by reference into the present specification, and in the aforementioned US Patent No. 9.536.702.

The plurality of secondary electron beamlets 9 pass through the first deflection system 110 and are deflected by the first scanning system 110 and directed by the beam splitter unit 400 to follow the secondary particle beam path 11 of the detection unit 200 . The plurality of secondary electron beamlets 9 travel in opposite directions from the primary charged particle beamlets 3, and the beamsplitter unit 400 is configured to connect the secondary particle beam path 11 to the secondary particle beam path 11, typically by means of a combination of magnetic or electromagnetic fields. The primary particle beam paths 13 are separated. Optionally, additional magnetic correction elements 420 are present in the primary particle beam path and the secondary particle beam path. The projection system 205 further includes at least a second deflection system 222 connected to the projection system control unit 820 . The control unit 800 is configured to compensate for residual differences in the positions of the plurality of focal points 15 of the plurality of secondary electron beamlets 9 so that the positions of the plurality of electron focal points 15 remain constant on the image sensor 207 .

The projection system 205 of the detection unit 200 includes at least a second intersection 212 of the plurality of secondary electron beamlets 9, in which the aperture 214 is located. In one example, the aperture 214 further includes a detector (not shown) that is connected to the projection control control unit 820 . The projection system control unit 820 is further connected to at least one electrostatic lens 206 of the projection system 205 , which includes further electrostatic or magnetic lenses 208 , 209 , 210 , and is further connected to the third deflection unit 218 . The projection system 205 further includes at least a first aperture modifier 220 having apertures and electrodes for influencing each of the plurality of secondary electron sub-beams 9, respectively; and an optional further active element 216 connected to to the control unit 800.

Image sensor 207 consists of an array of sensing regions whose arrangement pattern is compatible with the grating configuration of secondary electron beamlets 9 focused on image sensor 207 by projection lens 205 . This enables each individual secondary electron beamlet to be detected independently of other secondary electron beamlets incident on image sensor 207 . A plurality of electrical signals are created and converted into digital image data, which are processed by the control unit 800 . During image scanning, the control unit 800 is configured to trigger the image sensor 207 to detect a plurality of timely resolved intensity signals from the plurality of secondary electron beamlets 9 at predetermined time intervals, while the digital images of the image patches are accumulated and All scan positions from a plurality of primary charged particle beamlets 3 are stitched together.

The image sensor 207 shown in FIG. 1 may be an array of electronically sensitive detectors, such as CMOS or CCD sensors. Such electron-sensitive detector arrays may include electron-to-photon conversion elements, such as scintillator elements or arrays of scintillator elements. In another embodiment, the image sensor 207 may be configured as an electron-to-photon conversion unit or scintillator plate disposed in the focal plane of the plurality of secondary electron particle image spots 15 . In this embodiment, the image sensor 207 may further include a relay optical system for photon detection on dedicated photon detection elements such as multiple photomultiplier tubes or avalanche photodiodes (not shown) At the secondary charged particle image spot 15, the photons generated by the electron-to-photon conversion unit are imaged and guided. Such an image sensor is disclosed in US 9,536,702, which is incorporated herein by reference. In one example, the relay optical system further includes a beam splitter for splitting and directing the light to the first slow light detector and the second fast light detector. The second fast photodetector consists, for example, of an array of photodiodes such as avalanche photodiodes, which is fast enough to resolve the plurality of primary charged particle beamlets according to the scanning speed of the plurality of primary charged particle beams. The image signal of the secondary electron beam. The first slow light detector is preferably a CMOS or CCD sensor, which provides high resolution sensor data signals to monitor the focus 15 or a plurality of secondary electron beamlets 9 and to control the multiple beam charged particle microscope. The operation is described in more detail below.

In the illustrated example, the primary charged particle source is implemented in the form of an electron source 301 having an emitter tip and an extraction electrode. When primary charged particles other than electrons are used, such as helium ions, the configuration of the primary charged particle source 301 may vary from that shown. The primary charged particle source 301 and the active multi-orifice plate configurations 306.1 . . . 306.3 and the beam-steering multi-orifice plate 390 are controlled by the primary beamlet control module 830, which is connected to the control unit 800.

During the acquisition of image patches by scanning the plurality of primary charged particle beamlets 3, the platform 500 is preferably not moved, and after the image patches are acquired, the platform 500 is moved to the next image patch to be acquired place. Stage movement and stage position are monitored and controlled by sensors known in the industry, such as laser interferometers, grating interferometers, confocal microlens arrays, or similar instruments. For example, position sensing systems use any of laser interferometers, capacitive sensors, confocal sensor arrays, grating interferometers, or combinations thereof, to determine lateral and vertical displacement and rotation of the stage. As shown below in embodiments of the invention, the movement of the stage 500 from the first image patch to the next image patch overlaps with the capture of the image patch, and the throughput is increased.

A specific embodiment of a method for inspecting a wafer by capturing image patches is described in more detail in FIG. 2 . The wafer is placed with its wafer surface 25 in the focal plane of the primary charged particle beamlets 3 and with the center 21.1 of the first image patch 17.1. The predetermined locations of the image patches 17.1 . . . k correspond to inspection sites on the wafer for semiconductor feature inspection. From the detection file in the standard file format, the predetermined positions of the first detection part 33 and the second detection part 35 are loaded. The predetermined first detection site 33 is divided into a plurality of image patches, such as a first image patch 17.1 and a second image patch 17.2, and the first center position 21.1 of the first image patch 17.1 is in the multiple beam charged particle microscope. Below the optical axis is aligned for the first image capture step of the inspection task. The first center of the first image patch 21.1 is selected as the first local wafer coordinate system origin for capturing the first image patch 17.1. Methods of aligning wafers to register wafer surface 25 and generate a coordinate system of wafer coordinates are well known in the art.

A plurality of primary beamlets are distributed in each image patch in a regular raster configuration 41 and are scanned by a scanning mechanism to generate a digital image of the image patch. In this example, a plurality of primary charged particle beamlets 3 are arranged in a rectangular grating configuration 41, with N primary beam spots 5.11, 5.12 to 5.1N in the first row of n beam spots, and the Mth row With beam spot 5.11 to beam spot 5.MN. For simplicity, only M=five by N=five beam spots are shown, but the number of beam spots J=M by N could be larger and the plurality of beam spots 5.11 to 5.MN could have different grating configurations 41 , For example hexagonal or circular gratings.

Each primary charged particle beamlet scans across wafer surface 25, as in the example of a primary charged particle beamlet with beam spot 5.11 to 5.MN and scan path 27.11 to scan path 27.MN of the primary charged particle beamlet Show. For example, scanning of each of the plurality of primary charged particles is performed by moving back and forth along the scan paths 27.11...27.MN, and the scan deflector 110 causes each focal point of each primary charged particle beamlet to 5. MN moves together in the x-direction from the starting position of the image subfield line, which in this example is, for example, the leftmost image point of the image subfield 31.MN. Each focal point is then scanned by scanning a primary charged particle beamlet to the correct location, and then the scanning deflector 110 translates each of the plurality of charged particle beamlets into each individual subfield 31.11... 31. The line start position of the next line in MN. The movement back to the line start position of the next scan line is called flyback. A plurality of primary charged particle sub-beams follow in parallel scan paths 27.11 to 27.MN, thereby simultaneously acquiring a plurality of scan images of each subfield 31.11 to 31.MN. For image capture, as described above, a plurality of secondary electrons are emitted at the focal points 5.11 to 5.MN, and a plurality of secondary electron sub-beams 9 are generated. A plurality of secondary electron beamlets 9 are collected by the objective lens 102 , pass through the first deflection system 110 , and are directed to the detection unit 200 and detected by the image sensor 207 . The sequential data streams of each of the plurality of secondary electron beamlets 9 are transformed synchronously with scan paths 27.11 . . . 27.MN within the plurality of 2D data sets to form digital image data for each subfield. The plurality of primary charged particle beamlets follow predetermined scan paths 27.11 to 27.MN according to a preselected scan program. Finally, the digital images of the subfields are spliced together by the image splicing unit to form a digital image of the first image patch 17.1. Each image subfield is constructed to have a small overlap area with adjacent image subfields, as shown by the overlap area 39 of subfield 31.mn and subfield 31.m(n+1). The spacing between the plurality of primary charged particle beam spots 5.11 to 5.MN of the prior art typically varies due to drift, lens distortion and other aberrations. Therefore, the overlap region 39 of the prior art is generally constructed to be large enough to cover the entire image patch with one image scan, regardless of beam spot position fluctuations.

In a particular embodiment of the wafer inspection method, the throughput of a multiple beam charged particle microscope system for wafer inspection is increased by reducing the size of the overlap region 39 . This increases the size of each image patch and increases throughput. In one example, the beam spacing of the focal points 5 of the primary charged particle sub-beams is 10 μm. If the width of each 200 nm overlap region 39 is reduced, eg, by 25%, the image patch size increases by about 1% and the flux increases by about 1%. With a further 65% reduction in the width of the overlapping region, the flux increases by 2.5%. The reduction of the overlapping area 39 is achieved by controlling the spacing of the plurality of primary charged particle beamlets 3 . The position of the beam spot 5 formed by the plurality of primary charged particle beamlets 3 is controlled with high precision using a compensator such as the active multiple aperture plate 306.3 in Figure 1, such as a multiple beam multipole deflector device. For control operations, a detector for detecting the plurality of secondary electron beamlets 9, such as the image sensor 207 of the detection unit 200, is configured to provide sensor signals indicative of the positions of the plurality of beam spots 5 . The beam position deviations of the plurality of primary beam spots 5 are then corrected, and the overlapping area is reduced. By precisely controlling the primary charged particle beam spot 5 of each of the plurality of primary charged particle sub-beams 3 at the corresponding grating position with an accuracy of less than 70 nm, a 2% increase in flux is achieved. Through further precise control of the beam spot position of primary charged particles below 30 nm, the flux can be increased by more than 3.5%. In the next step, after capturing the digital image of the first image patch, the wafer is moved from the wafer stage to the adjacent predefined center position 21.2 under the control of the sensor, and a new local wafer coordinate system is defined, The center is at the predefined center position 21.2. A second image patch 17.2 is obtained, thereby obtaining two adjacent image patches 17.1 and 17.2, which have overlapping regions 19. Also, similar to the aforementioned reduction in overlap region 39, the size of overlap region 19 is reduced and the flux is increased. The two image patches 17.1 and 17.2 are stitched together to form an image of a predetermined wafer area. After capturing the digital image of the first inspection part 33, the wafer stage moves the wafer to the predetermined center position 21.k for image capture of the next second inspection part 35, such as inspecting the predetermined wafer area Execute a Process Control Monitor (PCM). A scan operation (not illustrated) is performed and image patches 17.k are obtained. With this method, several inspection sites of the wafer are inspected sequentially, as shown in this simplified example.

Next, the requirements or specifications of the wafer inspection task are described. For high throughput wafer inspection, image capture of image patches 17.1...k and stage movement between image patches 17.1...k must be fast. On the other hand, strict image quality specifications such as image resolution, image accuracy and repeatability must be maintained. For example, image resolution requirements are typically 2 nm or less with high repeatability. Image accuracy is also called image fidelity, for example, the edge position of the part, usually the absolute position accuracy of the part will be determined with high absolute accuracy. For example, the absolute lateral position of each of the plurality of primary charged particle beamlets must be known to an accuracy of less than 10 nm, and the absolute lateral position of each of the plurality of primary charged particle beamlets must be known to an accuracy of less than 1 nm. Typically, the positional accuracy requirement is about 50% lower than the resolution requirement. Second, high image consistency must be obtained. Image uniformity error is defined as dU = (Imax – Imin) / (Imax + Imin) with the maximum and minimum image intensities Imax and Imin of a homogeneous object under image capture. Typically, the image consistency error dU must be less than 5%. Image contrast and dynamic range must be sufficient to obtain an accurate representation of the semiconductor features and material composition of the semiconductor wafer being inspected. Typically, the dynamic range must be better than 6 or 8 bits, and the image contrast must be better than 80%.

At high image repeatability, it should be understood that with repeated image captures of the same area, first and second repeated digital images are generated, and the difference between the first and second repeated digital images is below a predetermined threshold. For example, the difference in image distortion between the first and second replicate digital images must be below 1 nm, preferably below 0.5 nm, and the difference in image contrast must be below 10%. In this way, similar imaging results can be obtained even by repeating imaging operations. This is important, for example, for image capture and comparison of similar semiconductor structures in different wafer dies, or for comparing acquired images with representative images obtained from CAD data or image simulations of databases or reference images .

One of the requirements or specifications for wafer inspection tasks is throughput. Throughput depends on several parameters, such as the speed of the sample stage, the time it takes for the stage to accelerate and decelerate, the number of repetitions required to align the sample stage at each new measurement location, and the amount of time required for each acquisition. Measure the area. An example of increasing the image patch size by reducing the overlapping area to increase throughput is described above. The measurement area per acquisition time is determined by dwell time, resolution and number of beamlets. Typical examples of dwell times are between 20 ns and 80 ns. Thus, the pixel rate at the fast image sensor 207 is in the range between 12 Mhz and 50 MHz, and approximately 20 image patches or frames can be obtained per minute. However, between capturing two image patches, the wafer is moved laterally from the wafer stage to the next relevant point. In one example, the time interval Tr of the wafer moving from the first image patch to the second image patch is about 1 second, and the frame rate is reduced to about 15 frames/minute. Typical time interval Tr for wafer movement from a first image patch to a second image patch using a standard stage, including a precision adjustment time interval of more than 1 second for the second image patch, may be 3 seconds or even longer , for example 5 seconds. A typical example of flux is about 0.045 sqmm/min (square millimeters per minute) in high-resolution mode with a pixel size of 0.5 nm for 100 beamlets, and the number of beamlets is larger and the resolution is lower, For example with 10000 beamlets and a dwell time of 25 ns, the flux may exceed 7 sqmm/min. Stage movement, including stage acceleration and deceleration, is one of the limiting factors for the throughput of multiple beam detection systems. Faster acceleration and deceleration of the stage in a short period of time often requires complex and expensive stages, or induces dynamic vibrations in multiple beam charged particle systems. Embodiments of the present invention achieve high throughput for wafer inspection tasks while maintaining image performance specifications well within the aforementioned requirements.

Often, fast and high-throughput image acquisition is degraded without control due to drift and dynamic effects, which include residual and unwanted stage motion. Typically, the deviation from ideal image capture conditions is described by an error function. An example of the error function in which the plurality of image spots 5 are rotated and displaced relative to the wafer 7 is shown in FIG. 3 a with an example of a circular configuration of the plurality of beam spots 5 . An image coordinate system 51 with image coordinates xi and yi is defined by a virtual coordinate system at the center of the image patch, as obtained by scanning a primary set of charged particle beamlets with beam spots 5 (eg three). The centerline of a set of primary charged particle beamlets at the predetermined central scan location is referred to as line of sight 53, such that line of sight 53 and the z-axis of the image coordinate system are the same. Ideally, and after proper calibration of the multiple sub-beam charged particle microscope 1, the line of sight 53 and the optical axis 105 of the multiple sub-beam charged particle microscope 1 are the same. In the actual imaging situation, the line of sight 53 is deviated from the optical axis 105 of the multiple sub-beam charged particle microscope system 1 . This deviation arises, for example, from drift of the object illumination unit 100 , aberrations in the first scanning deflector 110 or other electrostatic and magnetic elements in the primary charged particle beam path 13 , such as multiple sub-beam generator active elements 330 or splitters any of the beamers 400 . In the actual imaging situation, the deviation of the line of sight 53 varies with time, which includes the image capture time of one image scan of each image patch 17.1 . . . k.

A local wafer coordinate system 551 is defined at the inspection site of the wafer having local wafer coordinates x1 and yl. In the actual imaging situation, the local wafer coordinate system 551 deviates from the image coordinate system 51 with the line of sight 53 . Displacement vector 55 is caused, for example, by wafer stage misalignment, wafer stage drift, or image coordinate system 51 drift, or both. In the actual imaging situation, the deviation of the local wafer coordinate system 551 varies with time, which includes the image capture time of one image scan. The displacement vector 55 is generally described as the time correlation vector D(t)=[Dx, Dy, Dz](t). In the actual imaging situation, the displacement vector 55 includes the difference between the deviation of the line of sight 53 and the drift of the wafer stage 500, both of which vary with time, including the image capture time of one image scan of each image patch 17.1...k .

The image coordinate system 51 may be rotated about the z-axis or line of sight 53 by an angle of rotation Rz relative to the local wafer coordinate system 551, indicated by arrow 57, and obtained in the rotated image coordinate system 59 with coordinates (xi', yi') Image of image patch 17 from wafer surface 25 . The rotation angle can occur on any axis and can vary over time to form the rotation angle vector R(t) = [Rx, Ry, Rz](t). By rotating around the z-axis, all image spots 5 are rotated to image spots 5' (points indicated), as shown by the displacement vector 61 between the unrotated image spots 5 and the rotated image spots 5'. Aberrations caused by image rotation are caused by rotation of the image spot 5 or by rotation of the stage about the vertical axis or the z-axis or both.

Fig. 3b takes the image patch 17.1 of Fig. 2 as an example to illustrate the situation of image rotation. The same reference numbers as in FIG. 2 are used, but the imaging coordinate system 51 is rotated relative to the wafer coordinate system 551 . The plurality of focal points 5 arranged in a grating structure are rotated, the image patches 31 are rotated, and each scan path 27 is rotated. In an embodiment of the present invention, described in more detail below, the image rotation is compensated for by the rotation of the grating arrangement of the plurality of focal points 5 . This is different from the single-beam charged particle microscope, which can compensate for the image rotation through dynamic scanning rotation, that is, the rotation of the single scanning path is effectively realized by changing the single scanning path. The effect of scan rotation is illustrated at subfields 37.1 and 37.2 as an example of the effect of scan rotation on a plurality of primary charged particle beamlets in two primary charged particle beamlet examples. The scanning beam deflector of a multiple beam charged particle microscope can rotate the scanning path 27 , but the scanning deflector cannot rotate the grating structure of the multiple spots 5 . To compensate for the rotation, which includes dynamic changes in the rotation of the grating configuration of the plurality of light spots 5, additional components are required, as provided in some embodiments of the present invention.

Multiple sub-beam charged particle microscopy systems according to embodiments of the present invention include a plurality of sensors that provide sensor signals during image acquisition. The sensor is, for example, a stage position sensor of stage 500 , a sensor arranged at a hole such as hole 214 , or image sensor 207 . The control unit 800 is configured to extract an error function from the sensor signal, such as the image displacement vector D(t), the image rotation R(t), including focus position changes or image plane tilt. Typically, the control unit 800 is configured to analyze the sensor signal by methods known in the art and decompose the sensor signal into a set of individual model error functions, such as by fitting a set of predetermined model error functions with error amplitudes Compute to sensor data. Such a fitting operation may be, for example, a least squares fitting operation or singular value decomposition, and calculates a plurality of error amplitudes for each model error function in the set of model error functions. Through the calculation of error amplitudes, the amount of data used to control the plurality of primary and secondary charged particle beamlets 3 and 9 and stage 500 is significantly reduced to, for example, six error amplitudes. However, in particular embodiments of the present invention, a large number of error amplitudes, such as amplification errors, different higher order distortions and individual field-dependent image aberration patterns, are considered in the same way. The normalized error amplitude may describe, for example, displacement of the line of sight in both lateral directions, displacement of the wafer stage in the lateral and axial directions, rotation of the wafer stage, rotation of the line of sight, magnification error, focus error, astigmatism error or distortion error. By decomposing the sensor signal in a limited set of error amplitudes, the calculation and control speed of the correction signal is significantly increased.

In an example of a specific embodiment, the control unit 800 is configured to analyze the development of the error amplitude over time. A history of the variation of the error amplitude over time is recorded, and the control unit is configured to expand the variation of the error amplitude as a time-dependent model function. The control unit 800 is configured to predict changes in at least one subset of the error amplitudes over a short period of time, eg during a small fraction of the image scans of the scan time interval Ts. The scanning time interval Ts of the imaged patches was between 1 and 5 seconds, depending on the dwell time. In a typical example, the scanning time interval of one image patch Ts is about 3 seconds. In one example, slow changes in predicted changes in error amplitude (often referred to as drift) are separated from fast dynamic changes in predicted development of error amplitudes (often referred to as dynamics). In one example, the control unit 800 is configured to predict the change in at least a subset of the error amplitudes during the time interval Tr when the stage moves from the first image patch to the second image patch. The time interval Tr for moving the stage from the first image patch to the second image patch is between 0.5 seconds and 5 seconds. In one example, the control unit 800 is configured to predict the change in at least a subset of the error amplitudes during the time Td when the stage decelerates from the fast motion to the stop position. Typically, the control unit 800 is configured to extract at least one of a plurality of control signals based on the actuation output prediction model of the stage.

In an example of a specific embodiment, the error amplitude development of the slowly varying portion, the drift and the dynamically varying portion or the dynamic variation of the error amplitude, respectively, is extrapolated. For example, drift parts often exhibit linear or asymptotic behavior. For example, thermal effects often lead to slow drifts with asymptotic behavior. Using prior knowledge of the temporal error amplitude development, the drift development is derived based on a model function with predetermined asymptotic behavior, and the control unit 800 is configured to generate a control signal of the desired predicted error amplitude. The slowly varying development or drift of the error amplitude is separated from the fast development and, for example, the drift of the error amplitude is directly relayed to control the stage 500 . 4 and 5 illustrate representative error amplitudes over time. Figure 4a shows an example of a drifting or slowly varying error amplitude Sn(t) with a predetermined asymptotic behavior of the error amplitude model function 907 over time t. This behavior is typical for thermal drift or electrostatic or electromagnetic component drift, but other effects develop similarly over time. Other sources of drift can be variable electrostrictive force, or drift caused by charging of conductive parts or wafers during image scanning. During operation, the control unit 800 is configured to continuously derive the drift error amplitude Sn(t) from the sensor data. The operation time includes the first time interval Ts1 of the first image scan of the first image patch 17.1, the movement of the wafer stage from the first center position 21.1 of the first image patch 17.1 to the second center position of the second image patch 17.2 The time interval Tr of 21.2, and the second time interval Ts2 of the second image scan of the second image patch 17.2 (see reference numerals in FIG. 2). For example, over the actual time Ta during the first time interval Ts1, the time gradient 903 or model function 907 of the determined error amplitude Sn(t) is approximated to the measured error amplitude Sn(t). Using the error amplitude model function 907 or the gradient vector 903, the development of the error amplitude Sn(t) is predicted, and at a future time tc during the second time interval Ts2, the drifted part of the error amplitude Sn(t) reaches a predetermined critical value Sn_max, As shown by line 901 . The threshold is predetermined, for example, according to the specification of the image quality parameter related to the error vector Sn(t). In the time interval Tr between two subsequent image scans of the two image patches 17.1 and 17.2, the control unit 800 is configured to change the control value of the compensator accordingly, and by adjusting the active elements of the multiple beam charged particle microscope 1 to The drift component of the error amplitude Sn(t) is reduced. Active elements may include slow acting compensators, such as magnetic elements or stages. In particular embodiments of the invention, lateral drift of the line of sight 53 or image coordinate system 51 is compensated for, for example, by adding an offset to the lateral position of the wafer stage 500 , and shifts in focus position, for example, by adding an offset to the wafer stage 500 . z position to compensate. In particular embodiments of the present invention, the imaging magnification drift of the plurality of primary charged particle beamlets 3 causes the spacing of the plurality of primary charged particle beamlets 3 to vary, and for example by adding an offset current to the dedicated Magnetic lens elements to compensate. In a specific embodiment of the present invention, the rotational drift of the plurality of primary charged particle beamlets 3 as depicted in FIG. Correction to compensate, a primary charged particle beamlet is produced by adding an offset current to a second dedicated magnetic lens element (eg, objective 102). The results are illustrated in Figure 4b. With this adjustment, the corrected slowly varying drift error amplitude Sn(t) is controlled well beyond the error amplitude critical Sn_max. Since the drift portion varies slowly with time, the error amplitude Sn(t) can be adjusted and compensated at least in part during the time Tr between subsequent image scans. Therefore, a method of inspecting wafers using multiple beam charged particle microscopy is provided, the steps are as follows: The first image capturing step of the first image patch during the first time interval Ts1, movement of the wafer stage from the position of the first image patch to the second image patch during the time interval Tr, and a second image capturing step of the second image patch during the second time interval Ts2, whereby, During a first time interval Ts1, at least a first error amplitude is calculated from the plurality of sensor signals, During the first time interval Ts1, the first error amplitude is predicted to develop through at least the first time interval Ts1, the moving time interval Tr and the second time interval Ts2, And, at least during the moving time interval Tr, a control signal is provided to the control unit of the multiple beam charged particle microscope for keeping the predicted development of the error amplitude during the second time interval Ts2 below a predetermined threshold.

In one example, a prediction of the development of the first error amplitude is generated according to a prediction model or extrapolation.

In one example, a control signal is provided to the control unit of the multiple beam charged particle microscope for keeping the predicted development of the error amplitude below a predetermined threshold also during the image scanning of the time interval Ts1 or Ts2. For example, if a slow drift of the image coordinate system is predicted, the drift of the image coordinate system can be compensated by slow compensation motion of stage 500 so that Sn(t) is controlled well below the critical Sn_max during image capture.

Figure 5 illustrates the rapid dynamic changes in imaging bias described by the dynamic changes in the error amplitude Nn(t). Such dynamic changes in imaging bias may be introduced, for example, by internal noise sources (eg, vacuum pumps) or other internal noise sources (eg, vibrations caused by rapid acceleration and deceleration of the wafer stage). Other noise sources may be external sources.

The dynamic variation Nn(t) shows a simplified periodic behavior whose half-period is less than one scan time interval Ts1 or Ts2 of one image patch. In an embodiment of the present invention, the control unit 800 is configured to derive the dynamic variation of the error amplitude Nn(t) and to determine the control signal of the fast active element of the multiple beam charged particle microscope 1 at high speed. Such active elements are, for example, electrostatic beam deflection scanners or electrostatic correctors, which can be adjusted at high speed. During image scanning of the first image patch with scanning time Ts, the uncontrolled error amplitude Nn(t) exceeds at least twice the predetermined error amplitude window DNn of tc1 and tc2, denoted by reference numeral 905 . The error amplitude window 905 with upper and lower thresholds for the error amplitude Nn(t) represents the normative requirements for the image quality parameter represented by the error amplitude Nn(t). The control unit 800 is further configured to provide a dynamic control signal to the control unit of the fast active element such that the corrected dynamic deviation or error amplitude Nn(t) as shown in FIG. between critical. The control operator 800 is provided with a fast control loop, such as an open control loop, allowing adjustment and control at a bandwidth of at least 50 times, preferably at least 100 times, over an image scan frequency of about 0.3 Hz or a frame rate of 1/Ts, Or even better 1000 times. In one example, if imaging aberrations have been performed, then at a control frequency of about 2.5 kHz or higher, the calculation of the error vector and the acquisition of the control signal for compensation are performed at least once per line scan. Accordingly, electrical control signals include signals having a bandwidth in the range of 0.1 kHz to 10 kHz or more.

It should be noted that depending on the frequency response of the control loop of the control operator 800, the frequency of the corrected error amplitude Nn(t) shown in FIG. 5b may be different from the frequency of the uncorrected error amplitude Nn(t) shown in FIG. 5a.

In one example, the control unit 800 is configured to predict the dynamic variation of the error amplitude Nn(t). For example, by deriving the local gradient 909 at the time Ta of the error amplitude Nn(t), the control unit 800 is configured to derive the control signal for the dynamic control of the fast active element during the image scan of the time interval Ts1.

A source of drive error for wafer stage misalignment or drift is the time interval Tr provided for moving the stage from the first image patch 17.1 to the second image patch 17.2. In particular, the misalignment or drift of the wafer stage depends on the number of adjustment repetitions and the time Td required to decelerate the stage from the moving speed to the stop position near the second image patch 17.2. In an embodiment of the invention, the time interval between the image capture steps of the first image patch 17.1 and the second image patch 17.2 is significantly reduced and the throughput is increased. According to an embodiment of the present invention, a charged particle microscope operating method is provided, wherein a series of image patches are sequentially imaged in the image capturing steps, which includes a first image patch 17.1 in the first time interval Ts1. The first image capture and the second image capture of the second image patch 17.2 in the second time interval Ts2, and further include a wafer stage 500 for moving a wafer stage 500 from the first center position of the first image patch 17.1 21.1 move to the third time interval Tr of the second central position 21.2 of the second image patch 17.2 so that at least one of the first and the second time interval Ts1 or Ts2 has an overlap with the third time interval Tr . The total time interval from the start of the first time interval Ts1 to the end of the second time interval Ts2 is less than the sum of the three time intervals Ts1, Tr and Ts2, and the throughput is increased and the fast detection mode is realized. Figures 5a and 5c illustrate specific embodiments of such a rapid detection mode with high throughput. In the first example of Fig. 5a, the image capture of the second image patch 17.2 is started before the wafer stage 500 comes to a complete stop. During the time interval Td during which the wafer stage decelerates to the end position, image capture starts and the time interval Ts2 for image capture has an overlap with the deceleration time interval Td of the stage 500 . The deceleration time interval Td includes the repeated adjustment of the stage and the time required to completely stop the stage. After rapid movement, the stage may drift or oscillate or vibrate, the stage deceleration time interval Td includes the time required for the stage to decelerate until its position coincides with the line of sight of the multiple beam charged particle microscope with an accuracy below a first predetermined threshold and The dynamic positional stability is below a second predetermined threshold. The control unit 800 is configured to monitor or predict the expected lateral positions Xl(t), Yl(t) and the movement speed of the wafer stage 500 during the time Td. The control unit 800 derives control signals for the scanning deflection unit of the charged particle microscope to compensate for the residual motion of the wafer stage during the deceleration time Td by the variable offsets Dx(t), Dy(t) of the sight line 53 . The control unit 800 is configured to calculate the image capture start time of the second image patch 17.2 according to the predicted movement speed of the wafer stage. For example, the start time of the image capture time interval Ts2 of the second image patch 17.2 is determined as the time when the predicted speed of the wafer stage is below a predetermined threshold, so that the remaining motion of the wafer stage during the deceleration time interval Td can be compensated. The control unit 800 is configured to initiate image acquisition by scanning the second image patch 17.2 and provide a time function of the offset coordinates to the deflection unit to compensate for remnants of the wafer stage during at least a portion of the deceleration time interval Td motion, wherein the deceleration time interval has an overlap with the time interval Ts2 of the second image capture. Therefore, the time interval Tr' between the first image scan during the first time interval Ts1 and the second image scan during the second time interval Ts2 decreases.

Figure 5c illustrates a second example of this specific embodiment in more detail. In this example, the control unit 800 is configured to derive the start time r1 of the wafer stage acceleration during the first image capture time interval Ts1 of the first image patch so that the compensation for the wafer movement by the scanning deflector is at within the maximum range of scanning deflectors for charged particle microscopes. During image capture and during at least a portion of the time interval Tu for accelerating the wafer stage, the control unit 800 is configured to provide control signals to the deflection unit, and in this example, a lateral position offset of the coordinate system as previously described The error amplitude Nn(t) is within the specified critical range 905.1 of the lateral position shift of the first image patch, and the image capture continues after the start time ri of the wafer movement until the time interval Ts1 of the first image capture End time t1. During the wafer movement within the time interval Tr, the control unit 800 is configured to derive the second time interval Ts2 start time t0' for the second image capture of the second image patch, such that the effect of the wafer movement by the scanning deflector is The compensation is within the maximum range of the scanning deflector of the charged particle microscope and the lateral position shift of the coordinate system is within the specified critical range 905.2 of the lateral position shift of the second image patch. The second image capture starts at the start time t0' of the wafer movement period and ends at r2, when the wafer stage reaches the vicinity of its target position. Therefore, the time interval Tr' between the first image scan during the first time interval Ts1 and the second image scan during the second time interval Ts2 decreases. The overlapping time interval between the start t0' of the second image capture and the end time rs of the wafer stage deceleration time interval Tr is usually greater than the end time t1 of the first image capture and the acceleration of the wafer stage to the wafer stage The overlapping time intervals between the start times ri of the movement time interval Tr. In one example, the deceleration time interval Td of the wafer stage includes at least one repetition of precise alignment of the wafer stage during image capture of image patches at each detection site, whereby the control unit and the deflection unit control the wafer synchronously move and compensate for the predicted and monitored position of the wafer stage during wafer stage movement by providing a sequence or function of offset coordinates corresponding to the wafer stage position to the deflection unit. The repetition of precise wafer stage alignment is the repeated readjustment of the wafer stage position from a first position with a large deviation from the target position to a second position with a deviation from the target position below a predetermined threshold. In one example, the threshold is determined according to the reduction of the overlapping area between two adjacent image patches, eg, determined to be lower than 100 nm, lower than 50 nm, or even lower than 30 nm. Thus, throughput is improved by reducing the time interval between subsequent image acquisitions and reducing the overlapping area between adjacent image patches. In one example, the time interval between subsequent image acquisitions between the first and second image patches is reduced by a factor of two, and the throughput or frame rate of the multiple beam charged particle microscope is increased from about 10 to about 14 frames per minute number. In one example, the time interval between subsequent image acquisitions between the first and second image patches was reduced by a factor of three, and the throughput or frame rate of the multiple beam charged particle microscope was increased from about 10 to over 15 frames per minute and the throughput is increased by more than 50% through the image quality control method in the wafer moving process of this specific embodiment. In general, compared to the time intervals Ts1 and Ts2 required to capture each of the two distant image patches 17.1 and 17.2 and the time Tr required to move the sample from the first detection site to the second detection site, the The provided method allows the acquisition of images of at least two distant image patches 17.1 and 17.2 within a shorter time interval TG, where TG < Ts1 + Ts2 + Tr .

The development or separation of the error amplitude into drift and dynamic changes is achieved, for example, by means of fast Fourier analysis or moving average calculation methods. Other methods well known in the art can also be used. In one example, a predetermined threshold for the maximum gradient of the error amplitude variation is applied and decomposed into a linear drift with the maximum gradient and a residual dynamic variation where the error amplitude portion exceeds the maximum gradient. Subtracting the linear part of the error amplitude below the maximum gradient, the dynamic change is obtained by subtracting the evolution of the error amplitude from the linear drift. Determine the maximum gradient of the error amplitude based on the maximum speed of the compensator to compensate for linear drift. Such a slow-acting compensator can be, for example, a magnetic element of a multiple beam charged particle microscope. In another example, a predetermined threshold for the maximum frequency of change in error amplitude is applied, and the drift portion is determined by low-pass filtering the evolution of the error amplitude. In one example, dwell time, line scan rate and frame rate are considered for the separation of drift and dynamic parts. For example, the dwell time is 50 ns and the line scan rate is about 2.5 kHz. The control unit 800 and the fast compensator of the multiple beam charged particle microscope can compensate for imaging performance variations or deviations in the frequency range of about 10 kHz or higher. Thus, rapid and dynamic changes or deviations in imaging performance can be controlled during scanning of multiple lines using a plurality of primary charged particle beamlets. Therefore, during the image capture period of the time interval Ts of about 3 seconds, the dynamic changes are compensated for many times, such as the flyback each time the control frequency is about 2.5 kHz, and even each line scan when the control frequency exceeds 2.5 kHz. period, such as 5 kHz or 10 kHz or higher. For example, during the time interval Tr' between two consecutive image scans, the slow drift over the time interval of seconds is compensated for, for example, by a slow compensator in the time interval Tr' below about 0.5 seconds. To synchronize compensators with different response times, delay lines can be included in the control unit, for example.

Predictions of error amplitude development are computed from polynomial expansions and approximations of extrapolation (eg, linear extrapolation), but other higher-order extrapolations (eg, second- or higher-order extrapolations) are also available. The Runge-Kutta method gives an example of higher order polynomial extrapolation. In the case of a slowly changing compensator (eg moving wafer stage), the calibration performance of the slowly changing compensator (eg wafer) is controlled and monitored to enable prediction of the development of error amplitudes such as stage position. The prediction of error amplitude development may also follow a model, so-called model-based predictors that generate expected error amplitudes from a model function of the expected development of error amplitudes. Such predetermined model functions are generated, for example, by simulation or by representative testing operations of a multiple beam charged particle microscope, and are stored in the memory of the control unit 800 . In one example, this predetermined model function is individual for each individual multiple beam charged particle microscope. In many paradigms, estimates of misbehavior following predictive models include frequency analysis, low-pass filtering, and polynomial approximation.

The aforementioned development and extrapolation methods, such as separation of error amplitudes into drift and dynamics or application of model functions from prior knowledge, can be chosen differently for different deviations in image performance parameters described by the temporal development of error. In one example, the control unit 800 is configured to perform a series of operational steps during image capture of a series of image patches, including: A) Expand the data stream forming the data of the plurality of sensors into a set of error amplitudes, E) Capture a set of drift control signals and a set of dynamic control signals, and F) Provide the set of drift control signals to the slow-acting compensator, and G) Provide the set of drift control signals to the fast acting compensator.

In a specific embodiment, the control unit 800 is further configured to include step B of approximating the time development as at least one of the error amplitudes. In a specific embodiment, the control unit 800 is further configured to include step C of slowly changing the drift of at least one of the prediction error amplitudes. In a specific embodiment, the control unit 800 is further configured to include a step D of rapidly changing at least one of the prediction error amplitudes dynamically.

In an example, the configuration of the control unit 800 includes the execution of step G: providing the set of dynamic control signals to the fast acting compensator during the image scanning time interval Ts1 of a first image patch in a series of image patches .

In one example, the configuration of the control unit 800 includes the execution of step F: between a first image scan of a first image patch and a second subsequent image scan of a second image patch in a series of image patches During the time interval Tr, the set of drift control signals is provided to the slow acting compensator. The time interval Tr is defined as the time required for the wafer stage 500 to move from the first center position of the first image patch to the second center position of the second subsequent image patch to be obtained by scanning imaging with the multiple beam charged particle microscope 1. time interval. In one example, the configuration of the control unit 800 includes the execution of step F: providing the set of drift control parameters to the slow-acting compensator during an image scan time interval Ts of an image patch.

In one example, the configuration of the control unit 800 includes performing step G in the image scanning time interval Ts1 or Ts2 of the image patch in at least one overlapping time interval, the time interval overlapping with the time interval Tr for the stage movement . In one example, the at least one overlapping time interval is at least a portion of the time interval Tu for wafer stage acceleration, or at least a portion of the time interval Td for wafer stage deceleration, or both.

An embodiment of the present invention is a method of operation of a multiple sub-beam charged particle microscope system 1 for performing wafer inspection tasks, and a software product for such wafer inspection tasks. A method of performing a wafer inspection task comprising executing the software code of the aforementioned steps A to G, the method is further explained in more detail in FIG. 7 below.

In a specific embodiment of the present invention, the multiple sub-beam charged particle microscopy system 1 for wafer inspection therefore has various measures to compensate for drift, dynamic effects and residual and unwanted stage movement. An example is illustrated in FIG. 6 . The same reference numbers as in the previous figures are used and reference is made to the previous figures. A multiple beam charged particle microscope (1) for wafer inspection includes a charged particle multiple beam sub-beam generator (300) for generating a plurality of primary charged particle beamlets (3), and includes a first deflection system (110) ) to scan the wafer surface (25) arranged in the object plane (101) using a plurality of primary charged particle beamlets (3) to generate a plurality of secondary electron beamlets ( 9) The object irradiation unit (100). The plurality of secondary electron beamlets (9) are formed by a projection system (205) and a second deflection system (222) for imaging the plurality of secondary electron beamlets (9) onto the image sensor (207) ) of the detection unit (200) images and captures a digital image of the first image patch (17.1) of the wafer surface (25) during use. The multiple beam charged particle microscope (1) further comprises a wafer stage (500) having a stage position sensor (520) for scanning the wafer surface during the acquisition of the digital image of the first image patch (17.1) (25) is positioned and maintained in the object plane (101).

The multiple beam charged particle microscope 1 includes a set of compensators including at least first and second deflection systems (110, 222), and slow acting compensators, such as magnetic elements or mechanical actuators. In one example, the slow acting compensator includes wafer stage 500 . The set of compensators further includes a set of fast acting compensators (132, 232, 332), such as electrostatic elements or low mass mechanical actuators. The multiple beamlet charged particle microscopy system 1 is provided with a plurality of detectors including a stage position sensor (520) and an image sensor (207), configured to generate a plurality of sensor data during use. The plurality of sensor data includes position and orientation data of the sample stage (500) provided by the stage position sensor (520).

The multiple beam charged particle microscope 1 further includes a control unit (800), wherein the control unit (800) is configured to generate a first set of P control signals _Cp from the data of the plurality of sensors, so as to capture the first image patch The set of compensators are controlled during digital imaging of (17.1) such that operational control is achieved during use and the aforementioned specifications are maintained during image capture of a series of image patches.

During the stage movement of the stage 500 , the stage movement is monitored by the stage position sensor 520 . Stage position sensors 520 are known in the art and may include laser interferometers, grating sensors, or confocal lens array sensors. During the image scanning time interval Ts of one image patch in a series of image patches, the relative position of the wafer stage 500 is preferably controlled with high stability, eg, less than 1 nm, preferably less than 0.5 nm. As described above, between the first and second image scans of the first and second subsequent image patches, the stage 500 is triggered by the control unit 800 to move from the first detection portion to the second detection portion. At the second inspection site, a new local wafer coordinate system is defined, and the stage 500 is controlled by the stage control module 880 to be at its predicted position and to control the relative position to the line of sight with high stability. Stage position sensor 520 measures stage position and movement in six degrees of freedom with an accuracy of less than 1 nm, preferably less than 0.5 nm. In an example (not shown), the stage position sensor 520 is directly connected to the stage control module 880 for a direct feedback loop to control stage position and movement. However, this direct feedback loop and control of a wafer stage with high quality is generally slow and does not provide sufficient accuracy during image scanning. Feedback loops can cause unwanted stage jitter or lag. The stage position sensor 520 is thus connected to the sensor data analysis system 818 of the control unit 800 according to a particular embodiment of the invention.

According to an example of an embodiment, the control unit (800) further includes an image data capture unit (810) configured to reduce the image sensor data from the image sensor (207) during use, eg, to be smaller than the image sensor 10% of the image sensor data portion of the sensor data and provide the image sensor data portion to the sensor data analysis system (818). During use, the electronic sensitivity image sensor 207 receives a large image data stream of image sensor data of a plurality of secondary electron intensity values and feeds the image data to the image data capture unit 810 of the control unit 800 . A large amount of imaging data is not directly used to monitor the imaging operation of the multiple beam charged particle microscopy system 1 . A small portion of the image data stream is branched from the image data stream, and the image sensor data portion is directed to the sensor data analysis system 818 . For example, the image data acquisition unit 810 is configured to branch off secondary charged particle signals generated at predetermined scanning positions of the plurality of charged particle beamlets, or to extract a subset of secondary charged particle signals generated at the scanning charged particle beams The signal generated during the debounce period of 3 is forwarded to the sensor data analysis system 818. The predetermined scan position may be, for example, the row start position of a subset of scan lines, such as every fifth scan line, or the center position of each. In one example, image data for a subset of primary charged particle sub-beams, eg only one sub-beam at spot position 5.11 (see Figure 2), is used to generate the image sensor data portion. US 9,530,613, which is incorporated herein by reference, shows an example of a primary charged particle sub-beam dedicated subset configured at the periphery to provide a sensor signal for controlling a multiple beam charged particle microscope. US 9,536,702, which is incorporated herein by reference, shows an example of branching a dedicated subset of image data for each of a plurality of subfields for use in generating live view images. At least a portion of the live view image data can be applied as a portion of the image sensor data. The portion of image sensor data forwarded to sensor data analysis system 818 is significantly reduced by branching the signal from a predetermined subset of charged particle beamlets, or by using the signals at predetermined scanning locations of the charged particle beamlets to about less than 2%, less than 1%, preferably less than 0.5%, even better less than 0.1% or even less than 0.01% of the image data stream. In a specific embodiment, the image sensor 207 includes a first, slow and high resolution image sensor and a second, fast image sensor, as described above in connection with FIG. 1 . In this embodiment, the image sensor data is partially formed by the sensor data provided by the first slow image sensor, and the image data capture unit 810 is configured to combine the sensor data provided by the first slow image sensor. The data is provided to the sensor data analysis system 818 and the sensor signals of the second fast image sensor are provided to the image stitching unit 812 .

The image sensor data portion and stage position data from stage sensor 520 are combined in sensor data analysis system 818 . The sensor data analysis system 818 analyzes the image sensor data portion from the image sensor 207 and the position information from the stage sensor 520 and captures the wafer stage relative to the plurality of primary charged particle beamlets 3 The position information of the actual image coordinate system of , as explained in the example of FIG. 3 .

L。通常，感測器資料分析系統818構造成分析複數個感測器信號，並且通過本領域已知方法將多個傳感器信號分解成一組正常化誤差函數，例如通過該組正常化誤差函數對複數個感測器信號的擬合操作(fit operation)。The control unit (800) of the multiple beam charged particle microscope (1) includes a sensor data analysis system (818) configured to derive a sensor data vector DV of length L from the plurality of sensor data and analyze it The sensor data vector DV, and error functions such as image displacement, image rotation, focus position change and image plane tilt are extracted from the sensor data vector DV. The sensor data analysis system 818 is configured to compute, during use, the set of K amplitudes _Ak of the K error vectors, where K

L. Generally, the sensor data analysis system 818 is configured to analyze a plurality of sensor signals and decompose the plurality of sensor signals into a set of normalized error functions by methods known in the art, such as for the plurality of Fit operation of the sensor signal.

The control unit (800) further includes a control operation processor (840) for calculating a first set of control signals _Cp from the set of amplitudes _Ak of the error vectors. In the dynamic variation example of the lateral displacement of the image spot 5, the control operation processor 840 is configured to derive a correction or control signal for the dynamic variation of the error amplitude. The control _unit (800) is configured to compensate for the position of the wafer stage (500) or Orientation changes. Sensor data from image sensor 207 is synchronized and combined with information from stage position sensor 520 . The relative lateral displacement vector 55 between the local wafer coordinate system at the inspection site and the image coordinate system defined by the line of sight is derived by the sensor data analysis system 818 . The control operation processor 840 is configured to provide correction or control signals to the deflection control module 860 which controls the operation of the first scanning deflector 110 of the multiple sub-beam charged particle microscopy system 1 . As a result, the first electrostatic scanning deflector 110 controls the scanning operation of the primary charged particle beamlet 3 in synchronization with undesired dynamic changes of the wafer stage 500 in the lateral directions (here, the x and y directions). Meanwhile, the deflection control module 860 also controls the operation of the second scanning deflector 222 so that the positions of the plurality of secondary electron beamlets 9 on the image sensor 207 remain constant. Thus, the control unit 800 is configured to correct the scanning operation of the primary and secondary charged particle sub-beams through the first and second deflectors 110 and 222 to compensate for dynamic changes in the position of the stage 500 in the lateral direction, and to have high Image capture with high image fidelity and high image contrast remains well within the requirements or specifications of the wafer inspection task. Accordingly, the control unit 800 is configured to calculate and apply at least one additional voltage signal to the beam deflector 110 in the primary charged particle beam path 13 for generating additional displacement or rotation of the plurality of primary charged particle beamlets 3 during use , for at least partially compensating for lateral displacement or rotation of the stage relative to the line of sight. Accordingly, the control unit 800 is configured to calculate and apply at least a second additional voltage signal to the beam deflector 222 in the secondary electron beam path 11 to at least partially compensate for the electron beams originating from the plurality of primary charged particles during the adjustment scan Additional displacement or rotation of the secondary electron beamlets of the beam spot 5 of 3.

Next, an example of an error function is illustrated where wafer stage 500 is drifted in the vertical or z direction. The compensator group of the multiple beam charged particle microscope (1) comprises a compensator (332) of a charged particle multiple sub-beam generator (300), a fast compensator of an object irradiation unit (132) and a compensation of the detection unit (200) at least one of the devices (230, 232). Again, the image sensor data is analyzed in part by the sensor data analysis system 818 along with the stage position data from the stage position sensor 520 . The sensor data analysis system 818 analyzes the image sensor data portion from the image sensor 207 and the position information from the stage sensor 520 and captures the wafer relative to the actual scan position and a plurality of primary charged particles The position information of the line of sight of beam 3. The control operation processor 840 retrieves control signals for focus control of the plurality of primary and secondary charged particle beamlets 3 and 9 . The control operation processor 840 of the control unit 800 is thus connected via the primary beam path control module 830 to at least one fast compensator 332 of the multiple beamlet generator 300, such as an electrostatic focusing lens of the primary charged particle beam path 13, such as The electrostatic field lens 308 (see FIG. 1 ) or the fast compensator 132 of the object illumination unit controls the focal position of the plurality of primary charged particle beamlets 3 . The control operation processor 840 is further connected to the projection system control module 820 to control at least one fast compensator 232 of the detection unit 200 , such as the electrostatic focusing lens 206 (see FIG. 1 ), so that the image sensor 207 has a plurality of two The focus position of the sub-electron sub-beam 9 remains constant. Thereby, the primary beam path control module 830 and the projection system control module 820 compensate for the stage drift of the stage 500 in the vertical or z-direction and remain well within the requirements or specifications of the wafer inspection task with high contrast and High-resolution image capture.

In one example, the sensor data analysis system (818) of the multiple beam charged particle microscope (1) is configured to predict the temporal development of at least one amplitude An within the set of amplitudes _Ak in the error _vector . Some imaging lenses, such as objective 102 or beamsplitter element 420 (see FIG. 1 ), are magnetic elements that cause the beam paths of primary and secondary electron sub-beams 3 and 9 to rotate. Still image rotation or drift of image rotation is compensated for, for example, by a magnetic focusing element of the object illumination unit 100 . The control unit (800) is further configured to generate a third signal for positioning the wafer surface (25) in the object plane (101) by the wafer stage (500) for digital imaging of the second imaging patch (17.2) and wherein the control unit (800) is further configured to provide a second set of drift control signals from the plurality of sensor data for positioning the wafer stage (500) to the second image patch (17.2) control the set of compensators during the position. In one example, the control operations processor 840 is connected to the primary beam path control module 830 . The primary beam path control module 830 is connected to at least one slow compensator 130 of the object irradiation unit 100 or the magnetic element 430 of the beam splitter 400 (see FIG. 1 ) to correct the rotation of the set of primary charged particle beamlets 3 . Drift or slowly changing parts. In one example, the still image rotation is further compensated for by a predetermined rotation of the image sensor 207 . The control operation processor 840 is further connected to the projection system control module 820, which controls the slow compensator 230 of the secondary electron beam path, such as a magnetic lens. However, the magnetic element can only compensate for the drift portion of the rotation at a limited speed.

In one example, the charged particle multiple beamlet generator (300) further includes a fast compensator (332), and the control unit (800) is configured to calculate and provide at least one of the control signals of the first set of control signals _Cp . One gives a fast compensator (332) to cause rotation of the plurality of primary charged particle beamlets to compensate for the rotation of the wafer stage (500). For example, dynamic changes in the rotation of the wafer stage cause rapid changes and deviations of the plurality of primary charged particle beamlets relative to the predetermined orientation of the wafer stage. In this example, high speed is used to compensate for rotational dynamics. The control operation processor 840 is connected to the primary beam path control module 830 . The primary beam path control module 830 is further connected to the fast compensator 332 of the multiple beamlet generator 300, such as an active multiple aperture plate 306.3 (see FIG. 1), which in this example includes an array of electrostatic deflectors to individually and Each primary charged particle beamlet is rapidly deflected to compensate for undesired dynamic changes in the rotation of the set of primary beamlets 3 relative to the local wafer coordinate system. The projection system control module 820 is connected to the fast compensator 232 of the detection unit 200 , which includes, for example, a second multi-orifice plate with an electrostatic deflector array to compensate for the undesired rotational dynamics of the plurality of secondary electron beamlets 9 Variety. Thereby, image rotation during image scanning at one image pitch in a series of image pitches is compensated, and high image fidelity and image contrast are well maintained within wafer inspection task specifications.

In one example, stage position sensor 520 includes position and rotational sensitivity sensors, such as dual interferometers for each of the x-axis and y-axis.

In one example, compensation of wafer stage rotation is performed during the time interval Tr during which the wafer stage moves from the first image patch to the second image patch, as described above in connection with FIGS. 5a and 5c. Therefore, the throughput can be increased.

In a specific embodiment, the control operation processor 840 is further connected to the image stitching unit 812 . The image splicing unit 812 receives the large image data stream from the image data capturing unit 810, and converts the image data stream into 2D through time-series deconvolution of the data stream and image splicing of the image subfield 27 image to obtain an image patch 17 (see Figure 2). Several image patches, such as the first and second image patches 17.1 and 17.2, are stitched together to obtain a 2D image representation of the area of the wafer surface 25. To compensate for rapid image rotation, eg, through stage jitter and rapid rotation of wafer 7 relative to the image coordinate system, control operations processor 840 is configured to capture the remaining rotation of the plurality of image spots 5 during scanning, and to convert image spots 5 The remaining rotations are fed to the image stitching unit 812 . The image stitching unit 812 is configured to compensate for the residual rotation of the image patch 5 by known digital image processing methods to obtain a 2D image from a data stream of one image patch with high image fidelity. The final image is finally compressed and stored in the image data memory 814 .

In one example, the control operation processor 840 of the control unit 800 is configured to compensate for image rotation by simultaneous drift and motion compensation. Due to the limited range of image rotation compensation of multiple orifice plates arranged as a deflector array, the slowly varying drift offset can be continuously changed by drift compensators (130, 230, 330) comprising magnetic lenses, thereby allowing the The beam path 13 and the secondary electron beam path 11 are provided as multiple aperture plates of a deflector array to reduce and achieve the range of rapidly varying dynamic compensation.

Next, an example of an error function for forming a plurality of image spots 5 in an image plane inclined with respect to the wafer surface will be described. In this example, the control operation processor 840 derives a signal for correcting image tilt, which is forwarded to the primary beam path control module 830. The primary beam path control module 830 is configured to control the fast compensator 332 of the multiple beamlet generator 300 , such as the active multiple aperture plate 306 (see FIG. 1 ), which changes the focus position of each primary charged particle beamlet 3 , in order to effectively realize the inclined focal plane surface of the plurality of focal points 5 . Thereby, each primary charged particle beam 3 is focused at the wafer surface 25 even if the wafer stage 500 is tilted or its tilt angle is changed. The control operation processor 840 is further connected to the projection system control module 820 , which controls the fast compensator 232 of the detection unit 200 , which includes, for example, the multi-aperture corrector 220 . The fast compensator 232 of the detection unit 200 corrects the focal position of each or secondary electron sub-beam 9 so that the beam spot 15 remains constant within the focal position at the image sensor 207 . Therefore, the control operation processor 840 , the primary beam path control module 830 and the projection system control module 820 are configured to compensate for image tilt and maintain image capture with high contrast and high resolution throughout the image patch 17 .

In one example of the present invention and similar to the previous examples, a direct feedback loop is provided within the control unit 800 between the stage position sensor 520 and the first deflection yoke 110, and the control unit 800 is configured to receive feedback from the stage position sensor The stage position signal of the detector 520 is detected, and at least one first offset signal is provided to the first offset system 110 to compensate the movement of the wafer stage 500 and the movement of the wafer stage 500 by controlling the first deflection system 110 The deviation of the target position. The control unit 800 is further configured to provide at least a corresponding second offset signal to the second deflection yoke 222 . Thus, fast compensation for positional errors or movement of the wafer stage is provided and throughput is increased while maintaining the required specifications of the wafer inspection task.

The paradigms described above are of course not only occurring independently, but also simultaneously. The aforementioned apparatus and error correction method are not limited to the aforementioned examples. The control operations processor 840 is configured to simultaneously derive a control signal for a set of error amplitudes for a set of imaging biases through direct feedback or predictive correction or model-based correction as described above. In one example, the projection system control module 820 is further connected to the sample voltage source 503 to control the extraction field used to capture the secondary charged particles, thereby controlling the collection efficiency of the secondary electrons, which in turn also controls the secondary electrons. The intensity of the beam 9 and the kinetic energy of the secondary electrons. Kinetic energy correspondingly affects several other properties, such as image contrast. In one example, the projection system control module 820 is connected to further active elements 230 and 232 of the detection unit 200, such as the third deflection yoke 218, or a corrector, such as the multipole lens 216 (see FIG. 1). In one example, the sensor 238 of the secondary electron beam path provides additional sensor signals to the sensor data analysis system 818, eg, a sensor on an aperture element. In one example, the multipole sensor is arranged in the circumference of the aperture element 214 at the intersection 212 of the secondary charged particle beam paths 11 (see FIG. 1 ). Using the signal provided by the multipole sensor, the telecentric condition of the secondary charged particle beam path 11 is measured. In another example, the charged particle microscope 1 includes active and fast elements such as a beam steering multiple aperture plate 390 (see FIG. 1 ), eg for telecentric correction of a plurality of primary charged particle beamlets 3 . The beam steering multiple aperture plate 390 is connected to the primary beam path control module 830, which receives control signals through the control operation processor 840. In one example, sensor 138 is included within object illumination unit 100, which provides additional sensor signals to sensor data analysis system 818, such as sensors near aperture elements or on a multi-well plate. In an example, it includes an array of coils to measure electromagnetic noise at different orientations. In one example, the primary beam path control module 830 is connected to the source 301 and is configured to control the power supply or the amount of charged particles provided by the source 301 . Thus, a constant amount of charged particles is maintained over a series of image scans of a set of image patches. In one example, vibration sensors such as accelerometers or gyroscopes are connected to elements of a charged particle microscope, such as wafer stage 500 . The vibration sensor measures vibration and provides the signal to the sensor data analysis system 818 . Temperature sensors, such as in magnetic lenses or in cooling fluid return, provide an indication of system component status and approximate expected drift behavior of certain image qualities. For example, all sensor signals can be calibrated in a simulated inspection task for a test sample to provide representative sensor data for a wafer inspection task. The representative sensor data can be used to set the sensor data vector and extract the amplitude of the normalized error vector from the sensor data vector of the actual wafer inspection task.

Typically, the control operation processor 840 of the control unit 800 is configured to derive a correction signal from the error amplitude to compensate for slowly varying development of the error function, such as a slow drift of the stage 500 . The control operation processor 840 derives a fast compensation correction strategy for the dynamic change from the dynamic change of the error amplitude, and distributes the control signal to the primary beamlet control module 830, the projection system control module 820 and the deflection control module 860 , to compensate for rapid or dynamic changes in error amplitude, such as rapid vibration of the stage 500 . Drift and dynamic changes in error amplitude are calculated by the sensor data analysis system 818 of the control unit 800 and can be directly derived based on extrapolation or model based control. The correction strategy may follow a look up table, or by linear decomposition to decompose the error amplitude into predetermined correction functions provided by the different active elements of the charged particle microscope 1 . Therefore, the control operation processor 840 also monitors the actual state and state changes of the active elements of the charged particle microscope 1 . In one example, control operation processor 840 is configured to accumulate a history of control signals provided to active elements, such as secondary electron path active elements 230, 232, primary beam path active elements 330 and 332, deflector unit 110 or 222 , and thereby predict the actual state of the active elements of the charged particle microscope 1 .

One aspect of the present invention is to derive an error vector, and a drive signal to drive the compensator, to optimize image quality parameters during use of the multiple beam charged particle microscope, as shown in FIG. 1 in conjunction with FIG. 6 . This aspect is illustrated at the primary beam path, and similar considerations apply to the elements of detection unit 200 . In Figures 1 and 6, a typical subset of primary beam path elements of a charged particle microscope is illustrated, with a charged particle source 301, first and second collimating lenses 303.1 and 303.2, first and second active multiwell plates Configurations 306.1 and 306.2 (only one shown), first field lens 308, second field lens 307, third field lens 103.1 and fourth field lens 103.2, beam steering multiple aperture plate 390, first and second objective lens 102.1 and 102.2 (only one shown) as well as sample voltage source 503 and stage 500. The control unit 800 is configured to provide at least one control signal, eg voltage or current or both, to all of these elements during use. A multi-aperture configuration is provided with a variety of voltages, eg, at least a separate voltage for each of the plurality of primary charged particle beamlets. For a multiple sub-beam charged particle microscope system with 100 primary charged particle sub-beams, approximately 50 different drive signals are applied to the global elements during use, and approximately 200 to 800 different voltages are applied to each Multi-aperture configuration, and the number of single voltage or current can exceed the number of primary charged particle sub-beams by about 10 times. Prior to operation of a multiple sub-beam charged particle microscopy system according to an embodiment of the present invention, a set of image qualities are defined according to the specifications of the wafer inspection task. Some specifications are described above. The set of image qualities forms an image quality vector, and the amount of deviation in image quality corresponds to the amplitude of the error vector. For convenience, the set of error vectors is normalized to form a set of normalized error vectors. Sensitivity, ie, the amount of change in a set of imaging qualities relative to the drive signal applied to each element of each set of elements of the primary beam path, is determined, for example, by simulation or by calibration measurements. For example, in a calibration measurement, a representative sensor data set is measured by a set of sensors or detectors, and a sensor data vector is generated for each sensitivity. Sensitivity matrix of element sensitivities forming the primary beam path. The sensitivity matrix forms a linear perturbation model of the multiple beam charged particle microscope with respect to the set of image qualities relevant to the wafer inspection task, and is generally not orthogonal. For example, the sensitivity matrix is analyzed by singular value decomposition or a similar algorithm. For each image quality, at least one set of driving signals is selected as the control signal of the compensator to compensate for the deviation or aberration of the image quality, thereby reducing the The amplitude of the corresponding error vector. In one example, the sensitivity matrix is decomposed by splitting the matrix into two, three or more cores or subsets of independent sensitivity cores, corresponding to specific subsets of the image quality set. This reduces computational complexity and reduces nonlinear or higher-order effects.

In one example, at least one core of the sensitivity matrix is dependent on the temperature of the multiple beam charged particle microscope. For example, temperature changes in the barrel or barrel elements of a multiple beam charged particle microscope lead to focus shift, magnification shift, or astigmatism shift. Detectors provided in multiple beam charged particle microscopes include temperature detectors, such as temperature sensors in cooling water or attached to the interior of mechanical components, multiple well plates, or magnetic elements. Thereby, orthogonalization of the various cores of the sensitivity matrix can be performed at multiple representative temperatures, and the temperature corrected sensitivity matrix can be used to calculate the corresponding drive signal of the compensator from the temperature signal. Consideration of actual temperature and the application of temperature-corrected sensitivity matrices and corresponding drive signals are particularly relevant for the repeated calibration steps of a multiple beam charged particle microscopy system as described below. In a simplified example, multiple temperature sensors are reduced, and the expected temperature is predicted from the operating history of the multiple beam charged particle microscope system.

In one example, a first basis set of drive signals is selected for a fast compensator, eg comprising electrostatic compensators and deflectors, such as fast compensators 332 of multiple beamlet generators, first deflection system 110, object illumination unit 100 A second basis set of drive signals is selected for the fast compensator 132, and for a slow acting compensator comprising eg magnetic elements, like the slow compensator of the object illumination unit 130 in FIG. 6 . In one example, each basis set of drive signals is thus minimized to the minimum number of drive signals, thereby reducing the number of control operators for each component, shortening computation time, and the aggregation of image quality can be controlled within the wafer inspection task. within the requirements specification.

Each driving signal basis set is stored in the memory of the control unit 800 , for example, in the memory of the primary beam path control module 830 . Control operation processor 840 derives a set of control signals from the amplitudes of a set of error vectors. The primary beam path control module 830 derives the set of drive signals from the base set of drive signals, eg, by multiplying with the set of control signals calculated by the control operation processor 840 . The secondary beam path control module 820 derives the set of drive signals from the base set of drive signals, eg, by multiplying the set of control signals calculated by the control operations processor 840 .

Accordingly, a method of operating a multiple beam charged particle microscope in preparation for wafer inspection includes defining a set of image qualities and a set or normalized error vector describing a set of image qualities combined with a vector of sensor data deviation. Based on the imaging specification for the aforementioned wafer inspection task, a set of thresholds for the set or normalized error vector amplitudes are determined and a pre-selection of a set of compensators to perform multiple beam charged particle microscopy. The set of compensators includes a first deflection unit of the multiple beam charged particle microscope for scanning and deflecting a plurality of primary charged particles, and a first deflection unit for scanning and deflecting a plurality of secondary charged particle microscopes generated during use of the multiple beam charged particle microscope The second deflection unit of the secondary electron. The method of operation of a multiple beam charged particle microscope in preparation for wafer inspection further comprises: by varying at least one drive signal for each compensator in the set of compensators according to a linear and/or nonlinear perturbation model to determine Sensitivity matrix. This sensitivity matrix is analyzed, for example, by singular value decomposition or similar algorithms. In one example, the sensitivity matrix is decomposed by dividing into two, three or more kernels or independent subsets of image quality. This reduces computational complexity and reduces nonlinear or higher-order effects. The method of operation of the multiple beam charged particle microscope in preparation for wafer inspection further includes deriving a set of normalization drive signals to compensate for each of the set of normalization error vectors. The normalized error vector, the normalized drive signal and the critical group are stored in the memory of the multiple beam charged particle microscope control unit to form the predetermined error vector and the predetermined drive signal.

During use, such as during wafer inspection, the method of operation of the multiple beam charged particle microscope further includes receiving a plurality of sensor data from a plurality of sensors of the multiple beam charged particle microscope to form a sum of sensor data vectors step. In one example, the plurality of sensor data includes at least one of position or velocity information for maintaining actual wafer stage position and actual velocity of the wafer during inspection using multiple beam charged particle microscopy. The set of sensors used to generate the plurality of sensor data is prepared and constructed such that a predetermined error vector can be unambiguously derived, and during use, the actual amplitude of a set of normalized error vectors is derived from the sensor data vector , representing the actual state of image quality in multiple beam charged particle microscopy. A set of control signals is derived from the set of actual amplitudes, and a set of actual drive signals is derived from the predetermined normalized drive signal, eg by multiplying with the control signal. The control unit controls the compensators of the multiple beam charged particle microscope and provides the set of actual drive signals to the set of compensators so that the set of actual amplitudes remains below the set critical and the operation of the wafer inspection task is well maintained within imaging specifications within. In FIG. 7, the method of operation according to a specific embodiment of the present invention is explained in more detail. The same reference numbers in Figures 1-6 are used for illustration. For wafer inspection, the multiple beam charged particle microscope (1) includes a plurality of detectors including an image sensor (207) and a stage position sensor (520), and a set of A compensator, the set of compensators includes at least first and second deflection yokes (110, 222). In the memory of the control unit 800 of the multiple beam charged particle microscope (1), thresholds for the amplitude of the error vector and at least one set of normalized drive signals are stored.

In the first step SR, the wafer inspection task is logged in, for example, by an operator or instructions are provided by an external operating system. The loaded wafers are aligned and registered in a predetermined global wafer coordinate system of the multiple beam charged particle microscope system 1 . The wafer inspection task includes a series of inspection sites (eg, 33, 35 in Figure 2). From a sequence of inspection sites, a series of image capture tasks in a plurality of wafer regions at least at the first and second inspection sites 33 and 35 are generated. The at least one detection site may include at least first and second imaging patches 17.1 and 17.2. Each imaging patch of lateral dimension PX is imaged in the multi-beam charged particle microscope 1 by a plurality of primary charged particle beamlets 3 arranged in a grating array, wherein each of the plurality of primary charged particle beamlets 2 The user scans each subfield 31 of lateral dimension SX. The subfields scanned by the primary charged particle beamlets 3 are stitched together to form image patches 17 . The lateral size SX of the subfield is typically 10 μm or less, and the image size PX of one image patch 17 is typically about 100 μm or more. The number of primary sub-beams 3 is typically 10×10 sub-beams or even more bary sub-beams, eg 300 sub-beams or 1000 sub-beams. Preferred grating configurations are eg hexagonal gratings, rectangular gratings, circular gratings with sub-beams arranged at least in circles, but other grating configurations are also possible.

The first and second patch center positions 21.1 and 21.2 of the image patches 17.1 and 17.2 are calculated from the inspection task list, which includes the positions of the inspection sites 33 on the wafer surface and the area of the inspection task. If the lateral dimension of the detection site area exceeds the image patch, the detection site area is divided into at least two image patches 17.1, 17.2, with at least first and second patch center positions 21.1, 21.2. The first and second center patch locations 21.1, 21.2 are transformed in wafer coordinates and define the first and second local wafer coordinate systems relative to the global wafer coordinate system. Thereby, a plurality of local wafer coordinate system lists for capturing the corresponding image patches 17.1 and 17.2 are generated.

It should be understood that the first and second members are only used to illustrate multiple members each time, and these multiple members may also include more than two members, for example, a detection task may include multiple 50, 100 or more Detection sites, and each detection site may contain a plurality of 2, 4 or more image patches.

In step S1 , the state of the multiple sub-beam charged particle microscope system is determined, for example, from the operation history or from the initialization of the multiple sub-beam charged particle microscope 1 . The initialization of the multiple sub-beam charged particle microscopy system 1 may include system calibration if a corresponding trigger signal is provided. Selected sub-beams of the plurality of charged particle sub-beams 3 can be used for system calibration. At least one reference sample attached to a dedicated holder on the wafer stage 500 or the second metrology stage can be used for system calibration and line of sight 53 for determining the position of the charged particle microscope and the wafer stage. Two or more reference samples at different locations can be used to calibrate different image performance functions such as magnification, distortion or astigmatism.

Step S0 includes positioning the wafer surface ( 25 ) of the wafer and aligning it with the position of the local wafer coordinate system ( 551 ) in the line of sight of the multiple beam charged particle microscope ( 1 ). The wafer is positioned below the optical axis or line of sight 53 of the multiple sub-beam charged particle microscope 1 and aligned with the next local wafer coordinate system 551 . The next local wafer coordinate system 551 may be a first or any subsequent local wafer coordinate system 551 from the list of local wafer coordinate systems generated in step SR.

The wafer stage 500 is triggered to move the wafer so that the local wafer coordinate system 551 is aligned with the line of sight 53 of the charged particle microscope. Alignment of each local wafer coordinate system by moving the wafer stage is selectively performed by means of patterns formed or visible on the wafer surface. When the difference vector between the image coordinate system 51 and the wafer local coordinate system 551 with the line of sight 53 as the z-axis in the multiple beam charged particle microscope 1 is lower than a critical value, the adjustment is stopped. Difference vector 55 is, for example, a vector including six degrees of freedom for stage movement, including displacement and rotation or tilt. For fine-tuning, the difference vector is less than 50 nm or even less in the lateral direction, and can be less than 100 nm in the line-of-sight or focus direction. The threshold for image rotation in the z-axis is typically 0.5 milliradians, and the threshold for tilt relative to the x-y plane of the image coordinate system is typically 1 milliradian. Fine-tuning may include imaging steps of at least one detection site, and several repetitions of stage movement.

In a specific embodiment of the present invention, the fast mode of operation for wafer inspection tasks is selected, and the requirements for precision adjustment are relaxed, and the threshold is increased by a factor of 2 or even 10 times or even more, and the amount of residual difference over the threshold increases to Compensation is performed by the set of compensators of the multiple beam charged particle microscope 1 . For this purpose, the control unit 800 generates a plurality of offset error vector amplitudes and provides them to the following step S2.

In step S1, image capture is performed to capture a digital image of the first image patch (17.1) of the wafer surface (25), and to collect a plurality of detector data from a plurality of detectors. Perform detection tasks from a series of detection sites. Step S1 includes at least: In step S1-1, the image capture process starts with the scanning imaging of the first image patch 17.1. Each image patch 17 is preferably imaged using the stage 500 adjusted to coincide with the line of sight 53 of the multiple beam charged particle microscope 1 according to step S0, or using a stage moving at a low speed as described above. In step S1-2, in parallel with step S1-1, a plurality of sensor data are generated by a plurality of detectors. The plurality of detectors include at least the stage position sensor 520 and the image sensor 207 . In one example, the plurality of detectors further includes other detectors of the multiple sub-beam charged particle microscope, such as detectors 238 and 138, which generate sensor data during image capture. The plurality of sensor data may additionally include current or voltage applied to electrostatic and magnetic elements. Other examples of sensors that provide sensor data are, for example, temperature sensors, such as those monitoring temperature in cooling fluids or magnetic elements.

The imaging of step S1 - 1 includes generating a plurality of sets of secondary electrons at positions where the plurality of primary charged particle beamlets 3 interact with the wafer surface 25 . A plurality of secondary electron sub-beams 9 are formed from the secondary electrons. Each of the plurality of secondary charged particle beamlets 9 is detected separately to obtain a digital image of the image patch 17 at the corresponding local wafer coordinate system 551 .

其中剩餘誤差向量低於預定臨界。在計算誤差振幅A_K 期間，考慮步驟S0內產生的多個偏移誤差向量振幅或偏移誤差向量振幅的預測時間行為。在一範例中，K的大小為6，代表晶圓局部坐標系統與視線之間差異的六個自由度，但一般情況下，K大於6，例如誤差向量集合包括K = 14個誤差向量，其包括晶圓載台位置、局部晶圓坐標系統和視線、放大倍數變化、變形失真變化、像散、場曲、三階失真和色差的六個自由度差異。通常，K與L相比較小，即K＜L。形成感測器資料向量DV(i)的感測器資料之數量L可為10或更多，但L較佳為較小數量，以提高計算速度，例如K ＜ L ＜ 4 K。例如，如果K = 14，L較佳低於50。通過將複數個感測器資料減少到已減少長度L的錯誤向量和K誤差向量振幅，如此減少資料量，並且增加計算時間。 在S2-2中，根據多重射束帶電粒子顯微鏡在預測時間間隔內的預期發展，以預測該組實際振幅的至少一子集之發展振幅子集。推導出n個誤差振幅A_n 的至少一子集之時間發展，並且誤差振幅的子集被認為是時間相關函數A_n (t)。在實際時間T_a 之後的預測時間間隔內，誤差振幅A_n (t ＞ Ta)的時間發展之推導範例是從誤差振幅A_n (t ＜ T_a )的歷史外推，通過如前述的線性或更高階外推。因此，在使用期間，記錄多重射束帶電粒子顯微鏡的該組實際振幅的至少一子集，以用於產生該組實際振幅的子集歷史。誤差振幅A_n (t ＞ T_a )的時間發展推導之另一範例為誤差振幅A_n (t)的歷史到一組預定模型函數M_n (t)的近似。 在S2-3中，誤差振幅A_n (t)的至少一子集之時間發展分成振幅的時間發展中之漂移部分S_n (t)和動態變化N_n (t)，An(t) = S_n (t) + N_n (t)。During step S2, a plurality of sensor data are evaluated in the sensor data analysis system 818. Step S2 includes at least: In S2-1, combining a plurality of sensor data from different sensors with a sensor data vector DV( _i ) of length L at the actual time Ta, and combining the sensor data vector DV(i) of length L at the actual time Ta, The extended sensor data vector DV(i) in the set of K predetermined error vectors E _k (i). The set of predetermined error vectors E _k (i) represents the deviation of the image quality parameter set for image capture, as described above. Calculate a set of K error amplitudes A _k for the set of predetermined error vectors E _k (i) such that DV(i) =

where the residual error vector is below a predetermined threshold. During the calculation of the error amplitude _AK , the multiple offset error vector amplitudes or the predicted temporal behavior of the offset error vector amplitudes generated in step S0 are considered. In an example, the magnitude of K is 6, representing six degrees of freedom of the difference between the wafer local coordinate system and the line of sight, but in general, K is greater than 6, for example, the error vector set includes K = 14 error vectors, which are Six DOF differences including wafer stage position, local wafer coordinate system and line-of-sight, magnification change, deformation distortion change, astigmatism, field curvature, third-order distortion, and chromatic aberration. Typically, K is small compared to L, ie, K<L. The number L of sensor data forming the sensor data vector DV(i) may be 10 or more, but L is preferably a smaller number to improve the calculation speed, eg K < L < 4 K. For example, if K=14, L is preferably less than 50. By reducing the plurality of sensor data to error vectors of reduced length L and K error vector amplitudes, the amount of data is thus reduced and computation time is increased. In S2-2, a subset of developed amplitudes of at least a subset of the set of actual amplitudes is predicted based on the expected development of the multiple beam charged particle microscope over the predicted time interval. The time development of at least a subset of _n error amplitudes An is derived, and the subset of error amplitudes is considered to be the time correlation function An( _t ). An example of the derivation of the time development of the error amplitude An ( _t > Ta ₎ in the predicted time interval after the actual time Ta is to extrapolate from the history of the error amplitude An ( _t < Ta ₎ , by linear or Higher order extrapolation. Thus, during use, at least a subset of the set of actual amplitudes of the multiple beam charged particle microscope is recorded for use in generating a subset history of the set of actual amplitudes. Another example of the derivation of the time development of the error amplitude An ( _t >T _a ) is the approximation of the history of the error amplitude An (t) to a set of predetermined model functions _Mn ( _t ). In S2-3, the time development of at least a subset of the error amplitude An ( _t ) is divided into the drift part _{Sn (t) in the time development of the amplitude and the dynamic change N n (} t), An(t) = S _n (t) + N _n (t).

In one example, the predetermined error vector includes image aberrations introduced in the primary charged particle beam path. Aberrations in the primary charged particle beam path include distortions such as magnification errors, deformation distortions such as keystone distortion, or third and higher order distortions. Other aberrations are eg field curvature, astigmatism or chromatic aberration.

In one example, the predetermined error vector includes image aberrations introduced in the secondary electron beam path 11 . Aberrations in the secondary electron beam path 11, for example, reduce the collection efficiency of the secondary electrons, and lead, for example, to reduced image contrast and increased noise.

In one example, the combination of the plurality of sensor data and the sensor data vector DV(i) includes calculating the difference of the plurality of sensor data, such as the position coordinates of the line of sight of the multiple beam charged particle microscope and the stage The difference between the position sensor's position and orientation data.

In one example, a filter is applied to at least one of the time development of the error amplitude An ( _t ) such that a particular characteristic of the selected error amplitude is subtracted from the time development of the error amplitude An ( _t ). Therefore, the specific characteristics of the time development of the error amplitude An ( _t ) which do not affect the image quality are subtracted and the amount of control operations is reduced.

In one example, the set or error vector is derived from a set of compensator capabilities available in multiple beam charged particle microscopes such that the set or error vector can be compensated by controlling the actuation of the set of compensators. In one example, a set of possible error vectors is derived from imaging experiments, and the multiple beam charged particle microscope is provided with a set of compensators capable of compensating for the set of error vectors.

In one example, the amplitude or amplitude development of the set of error vectors is compared to a predetermined threshold set stored in the memory of the control unit 800 .

During a wafer inspection task, a set of predicted control signals and a set of predicted drive signals from the set of predicted control signals are determined based on the development of the amplitude, and the set of predicted drive signals is provided to the set of compensators in time sequence, thereby reducing the A subset of the actual amplitudes are reduced below their respective thresholds during the prediction time interval.

In step S3, a set of P control signals _Cp is derived from the set of error amplitudes _Ak . The deviation and amplitude of the error amplitude _Ak , which includes the time development of the error amplitude An of the error function _En , _is analyzed and mapped by the control operation processor 840 to a set of P control signals _Cp with a predetermined mapping function MF: MF: The mapping of A _k -> C _p K error amplitude sets to P control signal sets has a predetermined mapping function MF, eg by a look-up table, matrix inversion or numerical fitting operations such as singular value decomposition.

In one example, different sets of error vectors are processed in parallel in different error vector classes. For example, the coordinate system drift of the two coordinate system defined by the line of sight and the local wafer coordinate system are treated separately in the coordinate error category. Higher order imaging aberrations or telecentric aberrations are handled in their respective error vector categories. Thus, a set of control signals for a set of error vectors is calculated in parallel and at high speed.

In step S3-1, a set of deflection control signals is derived from a set of control signals _Cp .

In step S3-2, a set of primary control signals is derived from a set of control signals _Cp . The primary control signal is selected to control the compensator of the primary beam path to compensate for imaging aberrations such as defocus, image plane tilt, field curvature, magnification, astigmatism, chromatic aberration, telecentricity or other higher order aberrations.

In step S3-3, a set of secondary control signals is derived from a set of control signals _Cp .

In step S3-4, a set of image processing control signals is derived from a set of control signals _Cp . The set of image processing control signals includes a subset of image stitching components IS _p to be considered during image stitching.

In an optional step S3-5 (not shown), a set of carrier control signals is derived from a set of control signals _Cp .

In step S4, the set of control signals C _p is provided to at least one control module in the set of control modules, and the set of control modules includes a projection system control module 820, a primary beam path control module 830, a deflection control module group 860 , stage control module 880 and image stitching unit 812 . Each control module derives from the set of control signals _Cp a set of actuation values or drive signals, such as voltage or current sequences, to be provided to at least one compensator of the set of compensators to compensate for the set of actuation values or drive signals from the set of compensators or compensators The imaging disparity represented by an error vector of error vectors. During step S1 of image capture, a first control signal is provided to a set of compensators. A second subset of control signals is stored in memory and provided to step SO for application during positioning and aligning the next local wafer coordinate system.

In step S4-1, a set of deflection control signals are provided to the deflection control module 860. To compensate for a set of error vectors representing aberrations, the lateral positions of the focal points 5 of the plurality of primary charged particle beamlets 3 are first corrected so that the focal points are formed at predetermined lateral positions on the wafer surface 25, determined by the local wafer coordinate system 551 and a predetermined grating configuration with a lateral positional accuracy of less than 10 nm or less. The lateral alignment of the focal point 5 with the predetermined position is controlled by the first deflection unit 110 to deflect the plurality of primary charged particle beamlets 3 . Thereby, for example by providing a control signal C _p to the first and second deflection units ( 110 , 222 ), the position or orientation variation of the wafer stage ( 500 ) is compensated.

Therefore, an example of the control signal C _p of the deflection control signal group is the primary offset signal provided to the deflection control module 860 . The deflection control module 860 derives a first offset signal for the first deflection unit 110, which includes an electrostatic deflection scanner, and a plurality of primary charged particle beamlets 3 pass through the scanning path 27 with offset positions on the wafer surface 25 on scan. Thereby, the lateral displacement vector 55 between the local wafer coordinate system 551 and the line of sight 53 of the multiple beam charged particle microscope 1 is compensated, and a correction of the line of sight 53 is achieved such that its deviation from the local wafer coordinate system 551 is less than a predetermined threshold or, for example, less than 10 nm, 5 nm or even 2 nm, or even below 1 nm.

Furthermore, by providing the second offset signal to the second deflection unit 222, the focal point 15 of the secondary electron sub-beam 9 remains at a constant position at the image detector 207, and high image contrast and image fidelity are achieved. In order to maintain the position of the focal point 15 of the plurality of secondary electron sub-beams 9 at a constant position at the image sensor 207 , the plurality of secondary electron sub-beams 9 pass through the first deflection unit 110 and the second deflection unit 222 . After changing the scanning path 27 of the plurality of primary charged particle beamlets 5 on the wafer surface 25 with an offset position, the independent second deflection unit 222 provides the second offset signal of the deflection control signal group , and the offset position of the focal point 5 on the wafer surface 5 is compensated by the second deflection unit 222 so that the focal point 15 of the plurality of secondary electron beamlets 9 remains constant at the image sensor 207 .

The offset position may vary over time, and the offset control signal changes during the image scan of the image patch 17 . Thus, for example, lateral drift or jitter of the sample stage 500 is compensated.

In step S4-2, a set of primary control signals are provided to the primary beam path control module 830. In order to compensate for a set of error vectors representing aberrations, the longitudinal position of the focal points 5 of the plurality of primary charged particle beamlets 3 is corrected so that the focal points are formed on the wafer surface 25 with an accuracy lower than the depth of field of the multiple beam charged particle microscope . The depth of field of a multi-beam scanning electron microscope is generally around 10 nm-100 nm, and the maximum focal spot deviation from the image plane is less than 10 nm, preferably less than 5 nm. Aberrations at the focal point 5 of the plurality of primary charged particle beamlets 3 include defocusing, image plane tilt and field curvature.

For example, a primary control signal for correcting for image plane tilt is provided to the primary beam path control module 830, and the primary beam path control module 830 derives a set of focus correction voltages for the active multi-orifice plate configuration 306, For example a porous lens array. Thus, each focal position of each individual primary charged particle beamlet 3 is changed individually, and the image plane tilt is implemented to compensate, for example, the tilt of the sample stage 500 relative to the image coordinate system 51 .

In another example, the primary control signal used to correct for defocus is provided to the primary beam path control module 830, and the primary beam path control module 830 derives a voltage change for the field lens 306 to change z overall The image plane position in the direction. Therefore, the focal positions of the plurality of primary charged particle sub-beams 3 are changed to compensate, for example, the movement of the sample stage 500 in the z direction, that is, the propagation direction of the primary sub-beams 3 .

In another example, the primary control signal for correcting the rotation between the image coordinate system 51 and the local wafer coordinate system 551 is provided to the primary beam path control module 830, and the primary beam path control module 830 derives a Group deflection voltages for active multi-orifice plate configurations 306, such as multi-aperture deflector arrays. Thus, each individual primary charged particle beamlet 3 is deflected individually and a rotation of the image coordinate system 51 is effected to compensate, for example, the rotation of the sample stage 500 relative to the image coordinate system 51 .

Further control signals for correcting other aberrations of the primary beam path are accordingly provided. Imaging aberrations of the primary beam path include aberrations such as magnification variation, astigmatism, and chromatic aberration. The set of primary control signals includes control signals for compensators that control the path of the primary beam, including the charged particle multiple sub-beam generator 300 and the compensators of the object irradiation unit 100 .

In step S4-3, a group of secondary control signals are provided to the projection system control module 820. Imaging aberrations of the secondary beam path or detection unit are corrected in order to compensate for a set of error vectors representing aberrations.

For example, a secondary control signal for correcting image plane tilt is provided to projection system control module 820, and projection system control module 820 derives a set of focus correction voltages for use in multi-aperture corrector 220, such as a multi-aperture lens array . Thus, each focal position of each individual secondary electron sub-beam 9 is changed individually, and image plane tilt is achieved to compensate, for example, for the tilt of the sample stage 500 relative to the image coordinate system 51, and the two from the tilted wafer surface 25 The image of the sub-electron beam 9 is maintained on the image detector 207 .

In another example, a secondary control signal for correcting defocus is provided to the projection system control module 820, and the projection system control module 820 derives a voltage change for the electrostatic lens 206 to change the overall image flat position. Thereby, the focal position of the plurality of secondary electron beamlets 9 is changed to compensate, for example, the movement of the sample stage 500 in the z direction, the propagation direction of the primary beamlets, and the secondary electron beams from the defocused wafer surface 25 The image of beam 9 is maintained on image detector 207 .

In another example, a secondary control signal for correcting rotation between the image coordinate system 51 and the local wafer coordinate system 551 is provided to the projection system control module 820, and the projection system control module 820 derives a set of deflection voltages , for a multi-aperture corrector 220, such as a multi-aperture deflector array. Thus, each individual secondary electron beamlet 9 is deflected individually and compensates for the rotation of the image coordinate system 51 to image a plurality of secondary electron beamlets 9 at a constant, predetermined location on the image detector.

These examples combine to illustrate the compensation of aberrations in the primary beam path 13 and the secondary electron beam 13 . Some primary control signals are used to correct for example aberrations of the primary beam path, such as astigmatism or field curvature, are provided to the primary beam path control module 830 and aberrations are compensated in the primary beam path 13 only. Some secondary control signals are used to correct for example secondary beam path aberrations and are thus provided to projection system control module 820 and only compensate for aberrations in secondary beam path 11 .

In step S4-4, a group of image processing control signals are provided to the image stitching unit 812. The set of image processing control signals IS _p is directly applied or stored with the image data stream for application in image processing and image stitching operations performed by the image stitching unit 812 .

In operation S4-5 (not shown), a set of stage control signals is provided to the stage control module 880. In one example, slow drift of the sample stage 500 is detected in step S2 and compensated for by the stage control signal.

In one example, at least a subset of the control signal set _Cp is divided according to the time development separation of the drift portion _Sn (t) and at least a subset of the error amplitude An( _t ) in the dynamic variation Nn( _t ) are a subset of the drift control component CS _p and a subset of the dynamic control component CN _p . A subset of drift control components CS _p are provided to a set of compensators or active elements of a multiple sub-beam charged particle microscope system. In one example, the drift control component CS _p is provided to a subset of slowly varying active components comprising magnetic elements, and drives the slowly varying active components to change their states. In one example, the drift control component CS _p is provided to rapidly changing active elements such as electrostatic deflectors, electrostatic multipole correctors or electrostatic multi-aperture elements. In one example, the drift control component CS _p is provided to two subsets of compensators. A subset of the dynamic control components _CNp provide the rapidly changing active elements of the multiple sub-beam charged particle microscope system, and actuate the rapidly changing active components to vary their effect on the charged particle sub-beams. The rapidly changing active elements are electrostatic elements such as electrostatic deflectors, electrostatic multipole correctors, electrostatic lenses or electrostatic multiaperture elements.

K的數量K。每個控制信號C_p 可隨時間改變，並且至少一些控制信號C_p 在影像斑塊17的影像掃描期間改變。從而，例如在一個影像斑塊的影像擷取期間補償樣本載台500的橫向漂移。在一範例中，至少一控制信號為依賴於時間並且表示在隨後時間間隔中誤差振幅的預測發展之函數。藉此，實現用於補償預測成像偏差的連續控制操作。In general, the amount of the control signal P may exceed the error amplitudes _Ak and P

The number of K is K. Each control signal C _p may vary over time, and at least some of the control signals C _p vary during an image scan of an image patch 17 . Thus, for example, lateral drift of the sample stage 500 is compensated during image acquisition of an image patch. In one example, the at least one control signal is a function that is time-dependent and represents the predicted development of the error amplitude in subsequent time intervals. Thereby, a continuous control operation for compensating for the predicted imaging deviation is realized.

In step S5, a set of control signals _Cp comprising a subset of the drift control component _CSp and the dynamic control component _CNp is monitored and accumulated to record the change history of the multiple beam charged particle microscope.

In step S6, the actual system state of the multiple beam charged particle microscope is estimated from the change history.

In optional step S7, the time-development model function _Mn (t) is adapted to the change history of the multiple beam charged particle microscope and the actual system state and provided to step S2.

In step S8, the actual system state of the multiple beam charged particle microscope is analyzed and the development of the system state is predicted during subsequent image scans. If the prediction of the system state indicates that the error vector develops to a value that cannot be compensated, for example because the actuator range for compensation may be reached during the subsequent image scan, the actuation of the multiple beam charged particle microscope is triggered before the subsequent image scan recalibration and reset of the device. In this case, a trigger signal is supplied to step S1. If the prediction of the system state indicates that the next imaging task is possible, the method continues from step S0 to step S7 where image capture of subsequent image patches is performed at the next local wafer coordinate system from the inspection task list.

In one example, in step S8, the drift component of the control signal is calculated and provided to step S0, eg by predicting the development of the error amplitude. In step S0, the drift component is compensated by activating the compensator during the movement of the stage from the first image patch to the next second image patch or the next detection site. Therefore, in step S0, the control unit 800 provides a control signal to the stage control module 880 to move the stage 500 from the first local wafer coordinate system to the subsequent local wafer coordinate system, and also control the drift of the signal The components are provided to at least one of the control modules including primary beam control module 830 , projection system control module 820 or deflection control module 860 .

It is clear from the description that the steps S1 to S7 of the operating method are performed in parallel, and are performed in real time and interact with each other during the image capture of the image patch. Those skilled in the art will recognize that variations and modifications may be made to the foregoing methods.

In a specific embodiment of the present invention, the object plane 101 or the focal position of the plurality of primary charged particle beamlets can be changed while maintaining the specification requirements of the wafer inspection task. The reason for the change in the object plane 101 can be, for example, a predefined change in the imaging settings used for image acquisition, such as a change in magnification or a change in numerical aperture, a change in the desired resolution or placement in the primary beam path 13 or secondary beam Element drift within the beam path 11, eg monitored in step S7 or step S8. The change of the focal plane by the magnetic objective lens 102 of the multiple beam charged particle microscope 1 has the effect of rotating the plurality of primary charged particle sub-beams 3 . If the focal plane or object plane 101 changes, the grating configuration of the plurality of primary charged particle sub-beams is rotated relative to the optical axis 105 of the multiple beam charged particle microscope 1, as shown in FIG. 3, and the resulting image coordinate system 51 is relatively Rotate in the local wafer coordinate system 551 . The semiconductor structures disposed on the wafer surface 25 are generally structures disposed orthogonal to each other. As the image coordinate system or scan path 27 of the primary charged particle beam 3 rotates relative to the semiconductor structure configuration shown in Figure 3b, at least some of the specification requirements of high throughput wafer inspection tasks cannot be achieved. In addition, other image performance parameters are changed, such as the telecentricity of the plurality of primary charged particle beamlets, or the magnification or spacing of the plurality of primary charged particle beamlets. The plurality of secondary electrons emitted at the changing positions of the plurality of primary charged particle beam spots are collected by the adjusted objective lens 102, increasing the variation of image performance parameters. In this specific embodiment, unwanted changes in image performance parameters caused by changes in the image plane or focal plane are compensated by the control unit 800 . The control unit 800 is configured to predict the control signal to compensate for the error amplitude caused by the image plane position or focus position changing from the first image plane position to the second image plane position. The control unit 800 is configured to provide control signals to the primary beam spot 13 and compensators in the secondary beam path 11 and to the wafer stage. Compensators for the primary beam path include, for example, a second objective lens (not shown in FIG. 1 ), a field lens 103.1 or 103.2, a multi-aperture deflector array 306.3 or a multi-aperture deflector array 390 arranged near the intermediate image plane 321. Compensators for the secondary beam path include, for example, magnetic lenses, astigmatists or multi-aperture array elements. After the trigger image plane or focus position is changed from the first position to the second position, the control unit 800 controls a number of elements including a combination of compensators or wafer stages for the primary beam path and the secondary beam path.

In one example, the control unit 800 or the multiple beam charged particle microscope 1 is configured to derive from the plurality of sensor data, a description of the semiconductor structure orientation and image coordinate system 51 or scan path 27 or a plurality of primary charged particle beamlets The error vector of the deviation, and is further configured to derive a set of control signals and provide the set of signals to the control module. The control module is configured to effect at least one of rotation of the plurality of primary charged particle beamlets, rotation of the plurality of secondary electron beamlets, and rotation of the sample stage 500 . For example, the control unit 800 is configured to provide a control signal to step 0 of the aforementioned method to cause rotation by the slow motion compensator including the wafer stage 500 or the objective lens 102 . For example, the control unit 800 is further configured to provide control signals to cause rotation of a fast acting compensator, such as an electrostatic deflector array disposed in the primary charged particle or in the secondary electron beam path, or both.

In one embodiment, a method of operation of a multiple beam charged particle microscope configured for wafer inspection includes step a) loading into memory a set of predetermined normalized error vectors describing deviations from a set of image quality step b) loading into memory a set of predetermined thresholds for a set of predetermined normalized error vector amplitudes; and step c) loading a set of predetermined normalized drive signals for compensating each set in memory Normalize the error vector. During wafer inspection tasks, the method of operation of the multiple beam charged particle microscope includes step d) receiving a plurality of sensor data from a plurality of sensors of the multiple beam charged particle microscope to form a sensor data vector. In one example, the plurality of sensor data includes at least one of position or velocity information for maintaining actual wafer stage position and actual velocity of the wafer during inspection using multiple beam charged particle microscopy. During the execution of wafer inspection tasks, the method of operation of the multiple beam charged particle microscope further comprises the step e) determining a set of actual amplitudes of a predetermined normalized error vector from the sensor data vector, representing a set of multiple beam charged particle microscope image qualities step f) during wafer inspection, deriving a set of control signals from the set of actual amplitudes and deriving a set of actual drive signals from the set of predetermined normalized drive signals; step g) during wafer inspection During detection, the set of actual drive signals is provided to a set of compensators to reduce the subset of actual amplitudes below the subset of critical determined in step b) during operation of the multiple beam charged particle microscope. In one example, the method of operation of the multiple beam charged particle microscope further includes step h) during wafer inspection, predicting at least one of the set of actual amplitudes based on the expected development of the multiple beam charged particle microscope within the predicted time interval. A subset of the development amplitude of the subset. In one example, the expected development of the multiple beam charged particle microscope over the predicted time interval is determined from a predictive model function or one of a set of linear, second or higher order extrapolations of the actual amplitude history. The method of operating the multiple beam charged particle microscope further comprises step i) deriving a set of predictive control signals from the set of developmental amplitudes and deriving a set of predictive drive signals from the set of predictive control signals during wafer inspection; step j) During wafer inspection, the set of predicted drive signals is provided to the set of compensators in a time-sequential manner to reduce the subset of actual amplitudes to below a critical subset; and step k) during wafer inspection, recording at least a subset of the set of actual amplitudes of the multiple beam charged particle microscope for use in generating a subset history of the set of actual amplitudes.

The operation method of the multiple beam charged particle microscope is prepared by selecting the compensator set of the multiple beam charged particle microscope before operation. In one example, the set of compensators includes a first deflection unit of the multiple beam charged particle microscope for scanning and deflecting a plurality of primary charged particles, and for scanning and deflecting the multiple beam charged particle microscope during use of the multiple beam charged particle microscope The second deflection unit of the generated secondary electrons. The method of operation of the multiple beam charged particle microscope is also prepared prior to operation by determining a set of predetermined normalized error vectors describing deviations from a set of image quality, and by varying each compensation in the set of compensators according to a linear perturbation model A sensitivity matrix is determined from at least one drive signal of the device, and the set of predetermined normalization drive signals is determined from the sensitivity matrix to compensate for each of the set of predetermined normalization error vectors.

It will be appreciated that the components of the multiple beam charged particle microscope described in connection with FIG. 6 and the method steps described in connection with FIG. 7 are simplified examples for illustrating the set of multiple beam charged particle microscopes for wafer inspection according to the present invention. state and method of operation. At least some method steps or components may be combined, eg, the control operations processor 840 and the sensor data analysis system 818 may be combined in one unit, or the primary beam path control module 820 may be combined in the control operations processor 840.

At least one of the compensators used in the foregoing embodiments is a multiple beam active array element. Each of the primary charged particle sub-beams of the plurality of primary charged particle beamlets are individually influenced by an electrostatic microlens array, electrostatic astigmatism array, or electrostatic deflector array in the primary charged particle beam path. For example, such a multi-aperture array 601 is illustrated in FIG. 8 . The multi-aperture array 601 includes a plurality of apertures arranged in a grating configuration of a plurality of primary charged particle beamlets - in this example a hexagonal grating configuration. Two of the holes are designated by reference numbers 685.1 and 685.2. On the circumference of each of the plurality of holes, a plurality of electrodes 681.1-681.8 are arranged, in this example the number of electrodes is eight, but other numbers such as one, two, four or more are possible indivual. The electrodes are electrically isolated from each other and from the carrier of the multi-aperture array 601 . Each of the plurality of electrodes is connected to the control module by one of the conductive wires 607 . By applying an individual and predetermined voltage to each electrode 681, a different effect can be achieved for each of the plurality of primary charged particle sub-beams passing through each aperture 685. By using only electrostatic effects, the charged particle sub-beams transporting an aperture 685 can be individually adjusted or varied at high speed and high frequency. For example, the effect may be deflection, focal plane change, astigmatism correction of primary charged particle beamlets. In one example, multiple, eg, two or three, such multiple-well plates are arranged in sequence. Each of the secondary electron sub-beams of the plurality of secondary electron sub-beams are individually each similarly subjected to an array of electrostatic microlenses, electrostatic astigmatism, or electrostatic deflector arrays in the secondary electron beam path. Influence.

Next, another specific embodiment of the present invention is explained in more detail. A multiple beam charged particle microscope configured for wafer inspection and a method of operating such a microscope is described with reference to FIG. 1 . As can be understood from the above description, during the acquisition of a digital image such as the first image film 17.1, the plurality of primary charged particle beamlets 3 and the plurality of secondary electrons 9 are jointly scanned by the first electron beams in the shared beam path. The deflection system 110 is deflected, and the plurality of secondary electrons 9 are further scanned and deflected by the second deflection system 222 in the secondary beam path 11 of the detection unit 200 . Thereby, the focal points 15 of the plurality of secondary electron sub-beams 9 on the image sensor 207 are maintained at a constant position during the image scanning. The detection unit 200 includes an aperture 214 through which a plurality of secondary electron beamlets 9 are filtered. Aperture filter 214 thus controls the topological contrast of the secondary electron beamlets provided to image sensor 207 . The image contrast changes due to deviations of the detection unit 200 , for example due to the deviation of the centers of the intersections 212 of the secondary electron beamlets 9 , or the deviation of the second deflection yoke 222 . According to this particular embodiment, undesired changes in topological contrast are detected and compensated. Therefore, the detection unit 200 includes the third deflection system 218, and by the combined action of the first, second and third deflection units 110, 222 and 218, the center of the intersection 212 of the plurality of secondary electron beamlets 9 is maintained Coinciding with the aperture stop position of aperture stop 214 , the position of secondary charged particle image spot 15 remains constant on image sensor 207 . Thus, wafer inspection can be performed according to the specification requirements of the wafer inspection task. A constant image contrast is maintained for each of the plurality of secondary electron sub-beams on scan paths 27.11...27.MN and within different subfields 31.11...31.MN of image patch 17.1. The positions of the second and third deflection yokes 222 and 218 in the projection system 205 of the detection unit 200 are illustrated in FIG. 1 by way of example, while other positions of the second and third deflection yokes 222 and 218 in the projection system 205 may be A constant image contrast is achieved on the image sensor 207, as well as a constant position of the focal point 15 of the plurality of secondary electron beamlets 9. For example, the second and third deflection yokes 222 and 218 may be configured in front of the aperture filter 214 . The control unit 800 is configured to derive from the sensor data vector an error vector amplitude representing the contrast variation on the plurality of secondary electron beamlets 9, and is further configured to derive a first control signal and provide the first control signal to the deflection Control module 860. The deflection control module 860 is configured to derive a deflection drive signal to a deflection yoke including the second and third deflection yokes 222 and 218 disposed in the secondary beam path 11 of the detection unit 200 . In one example, the control module 800 is further configured to derive a second control signal and provide the second control signal to the projection system control module 820 . Projection system control module 820 is configured to derive a second drive signal to control other fast compensators 232 of projection system 205 , such as electrostatic lenses or astigmatism of multi-array active elements 220 . Thus, image contrast is well maintained within performance specifications for wafer inspection tasks with high throughput. In another example, the first deflection system 110 for scanning and deflecting the plurality of primary charged particle beamlets 3 is preferably located near the first beam intersection 108 of the plurality of primary charged particle beamlets 3 . However, due to the deviation of the primary beam path 13, the position of the first beam intersection 108 may deviate from its designed position and introduce telecentricity errors of the plurality of primary charged particle beamlets 3. The control unit 800 is configured to derive from the sensor data an error vector amplitude representing the deviation of the telecentric illumination of the plurality of primary charged particle beamlets 3 to the wafer surface 25, to derive a control signal from the deviation, and to provide a drive signal, eg, to Multi-aperture deflector 390 near intermediate image plane 321. Thereby, the telecentric illumination of the wafer surface by the plurality of primary charged particle beamlets 3 is maintained. Telecentric illumination means illumination in which each of the plurality of primary charged particle sub-beams 3 impinges on the wafer surface 25 parallel and almost perpendicular to the wafer surface 25 , eg with an angular deviation from the surface normal of less than 25 milliradians . In a specific embodiment, the actual error amplitude derived from the sensor data vector represents the image performance specification of the wafer inspection task, such as the line of sight of the wafer stage for the MLM and MLM image coordinates Relative position and orientation of the system, telecentric conditions, contrast conditions, absolute positional accuracy of multiple charged particle beamlets, magnification or spacing of multiple beam charged particle microscopes, or a single charged particle beam of multiple beam charged particle microscopes at least one of the beam numerical apertures. Other deviations from image performance specifications for wafer inspection tasks, such as higher-order aberrations such as distortion, astigmatism, and chromatic aberration of multiple charged particle beamlets, can also be monitored and compensated for during image scanning. For example, an error vector amplitude representing astigmatism can be derived from the image sensor data portion and compensated by an electrostatic compensator. The error vector amplitude representing the chromatic aberration of the primary charged particle sub-beam can be compensated, for example, by the additional magnetic lens 420 of the beam splitter unit 400 and the voltage supply unit 503 . Using a multiple beam charged particle microscope according to the specific embodiments or examples given above, it is possible to achieve fast scanning of the wafer surface and provide high-pass imaging of integrated semiconductor components with critical dimension resolutions at least down to a few nanometers. Quantitative inspection, such as below 2 nm during development or manufacturing or during reverse engineering of semiconductor devices.

A plurality of primary charged particle sub-beams are scanned in parallel on the wafer surface, generating secondary charged particles and forming digital images of image patches, eg, 100 μm – 1000 μm in diameter. After capturing the first digital image of the first image patch, move the substrate or the wafer stage to the next second image patch position, and obtain the second image patch by scanning a plurality of primary charged particle beams again A second digital image of the block. During operation and during each image capture, a plurality of sensor data is generated by a plurality of detectors including an image sensor and a stage position sensor, and a set of control signals are generated. Control signals are provided to a control module that controls the action of active elements, such as deflection units, electrostatic lenses, magnetic lenses, astigmatists or active multi-aperture arrays for scanning multiple primary and secondary charged particle sub-beams or other compensators. For example, between the capture of the first and second digital images, and as the stage moves from the first image patch to the second image patch, at least a portion is compensated, for example, by a slow compensator such as a magnetic element Imaging aberrations. During image capture of the digital image of the first or second image patch, a subset of control signals is provided to a control module including a deflection unit. Thereby, position errors or drifts of the wafer stage relative to the line of sight of the multiple beam charged particle microscope are compensated for, for example, during image scanning. Other aberrations or deviations from imaging performance specifications are determined and predicted from the sensor profiles, and corresponding control signals are generated and provided on-the-fly to the fast actuators. Thus, by stitching together multiple image subfields or patches, high-resolution digital images with high image fidelity and high precision and sub-5 nm or 2 nm or 1 nm resolution are formed. The stage is moved between the first and second image patches or to the next position of interest, eg the next PCM or adjacent image field, at high speed and eg reducing the number of precise stage alignment repetitions.

It will be apparent from the description that combinations and various modifications of examples and specific embodiments are possible and that specific embodiments or examples may be equally applicable. The charged particles of the primary beam can be, for example, electrons, but also other charged particles, such as helium ions. Secondary electrons include secondary electrons in a narrow sense, but also include any other secondary charged particles produced by the interaction of a beam of primary charged particle sub-beams with the sample, such as backscattered electrons produced by backscattered electrons or second-order ones. secondary electrons. In another example, secondary ions may be collected instead of secondary electrons.

Some specific embodiments may be further described using the following sets of items. However, the present invention should not be limited to any one of these sets of items: first group of projects

Item 1: A method of operating a multi-beam charged particle microscope (1) with high throughput and high resolution, comprising: A first image capture of a first image patch 17.1 in a first time interval Ts1 and the second image capture of the second image patch 17.2 in the second time interval Ts2; and a third time interval for moving the wafer stage (500) from the first center position (21.1) of the first image patch (17.1) to the second center position (21.2) of the second image patch 17.2 Tr, such that at least one of the first and the second time interval Ts1 or Ts2 has an overlap with the third time interval Tr.

Item 2: The method of operation of the multiple beam charged particle microscope (1) of item 1, wherein the second image is started before the third time interval Tr ends, that is, before the wafer stage (500) has come to a complete stop Second image capture of plaque 17.2.

Item 3: The operation method of the multiple beam charged particle microscope (1) according to item 1 or 2, wherein the third time interval Tr of wafer movement is before the end of the time interval Ts1, that is, when the first image patch 17.1 Start before an image capture is complete.

Item 4: The operating method of the multiple beam charged particle microscope (1) according to any one of Items 1 to 3, which further comprises calculating performed during the first time interval Ts1 of the image capture of the first image patch 17.1 The start time of the third time interval Tr for wafer movement is calculated such that the positional deviation between the first center position of the first image patch 17.1 and the line of sight (53) of the multiple beam charged particle microscope (1) or the wafer carrier The moving speed of the table (500) is below a predetermined threshold.

Item 5: The operating method of the multiple-beam charged particle microscope (1) according to any one of Items 1 to 4, further comprising calculating the second image captured during the time interval Tr of the wafer stage movement The start time of the time interval Ts2 such that the positional deviation of the second center position 21.2 of the second image patch 17.2 from the line of sight (53) of the multiple beam charged particle microscope (1) or the movement of the wafer stage (500) The speed is below a predetermined threshold.

Item 6: The operation method of the multiple-beam charged particle microscope (1) according to any one of items 1 to 5, further comprising the following steps: predicting a series of wafer stage positions during the time interval Tr of the movement of the wafer stage (500); calculating at least first and second control signals from the predicted wafer stage position; The first control signal is provided to a first deflection yoke (110) in the primary beam path (13) of the multiple beam charged particle microscope (1), and the second control signal is provided to the multiple beam charged A second deflection system (222) in the secondary beam path (11) of the particle microscope (1).

Item 7: A multi-beam charged particle system (1) with high flux and high resolution, comprising: a charged particle multiple beamlet generator (300) for generating a plurality of primary charged particle beamlets (3); An object irradiation unit (100) comprising a first deflection system (110) for scanning a wafer surface (25) arranged in the object plane (101) using a plurality of primary charged particle beamlets (3) to for generating a plurality of secondary electron beamlets (9) emitted from the wafer surface (25) at spot positions (5) of a plurality of primary charged particle beamlets (3), A detection unit (200) having a projection system (205), a second deflection system (222) and an image sensor (207) for imaging a plurality of secondary electron beamlets (9) on on an image sensor (207) and during use to capture digital images of a first image patch (17.1) and a second image patch (17.2) of the wafer surface (25); A wafer stage (500) including a stage motion controller, wherein the stage motion controller includes a plurality of motors configured to be independently controlled, the stage configured for capturing the first image patch (17.1) and during digital imaging of the second image patch (17.2), positioning and maintaining the wafer surface (25) within the object plane (101); a plurality of detectors including the stage position sensor (520) and the image sensor (207), the detectors configured to generate a plurality of sensor data during use, the sensor The data includes the position data of the wafer stage (500); A control unit (800) configured to perform, during use, a first image capture of a first image patch 17.1 in a first time interval Ts1 and a second image in a second time interval Ts2 second image capture of patch 17.2 and configured to trigger the wafer stage (500) during a third time interval Tr to remove the wafer stage (500) from the first image of the patch (17.1) The center position (21.1) is moved to the second center position (21.2) of the second image patch 17.2 so that at least one of the first and the second time interval Ts1 or Ts2 has an overlap with the third time interval Tr .

Item 8: The system of item 7, wherein the control unit is further configured to determine the start of a third time interval Tr of wafer movement during a first time interval Ts1 of image capture of the first image patch 17.1 time, so that the positional deviation between the first center position of the first image patch 17.1 and the line of sight (53) of the multiple beam charged particle microscope (1) or the moving speed of the wafer stage (500) is lower than a predetermined threshold .

Item 9: The system of item 7 or 8, wherein the control unit is further configured to determine the start time of the second time interval Ts2 of the second image capture during the time interval Tr of the wafer stage movement, such that The positional deviation of the second center position 21.2 of the second image patch 17.2 from the line of sight (53) of the multiple beam charged particle microscope (1) or the moving speed of the wafer stage (500) is below a predetermined threshold.

Item 10: The system of any of items 7 to 9, wherein the control unit is further configured for predicting a series of wafer stage positions during the time interval Tr of the movement of the wafer stage (500), and for At least first and second control signals are calculated from the predicted wafer stage position and used to provide the first control signal to the first deflection yoke ( 110 ) in the primary beam path ( 13 ) and to provide the second control signal A control signal is provided to a second deflection system (222) in the secondary beam path (11) of the multiple beam charged particle microscope (1).

Item 11: A method of operating a multi-beam charged particle system (1) with high flux and high resolution, comprising: A first image capture of a first image patch 17.1, a second image capture of a second image patch 17.2 and the wafer stage (500) from the first center of the first image patch (17.1) The position (21.1) is moved to the second center position (21.2) of the second image patch 17.2, all within a time interval TG in The first image capture of the first image patch 17.1 is during the first time interval Ts1; The second image capture of the second image patch 17.2 is during the second time interval Ts2; and During a third time interval Tr, the wafer stage (500) is moved from a first center position (21.1) of the first image patch (17.1) to a second center position (21.2) of the second image patch 17.2 ); and in which The time interval TG is less than the sum of Ts1, Ts2 and Tr: TG < Ts1 + Ts2 + Tr.

Item 12: A multiple beam charged particle microscope (1) for wafer inspection, comprising: a charged particle multiple beamlet generator (300) for generating a plurality of primary charged particle beamlets (3); An object irradiation unit (100) comprising a first deflection system (110) for scanning a wafer surface (25) arranged in an object plane (101) with a plurality of primary charged particle beamlets (3) for scanning with a plurality of primary charged particle beamlets (3) generating a plurality of secondary electron beamlets (9) emitted from the wafer surface (25) at the scanning spot position (5) of the plurality of primary charged particle beamlets (3); A detection unit (200) having a projection system (205), a second deflection system (222) and an image sensor (207) for imaging a plurality of secondary electron beamlets (9) on on an image sensor (207) and during use to capture digital images of a first image patch (17.1) and a second image patch (17.2) of the wafer surface (25); Wafer stage (500) with stage position sensor (520) for positioning and maintaining the wafer surface (25) in the object during acquisition of digital images of the first image patch (17.1) in plane (101) and for moving the wafer surface from the first image patch (17.1) to the second image patch (17.2); a plurality of detectors including the stage position sensor (520) and the image sensor (207), the detectors configured to generate a plurality of sensor data during use, the sensor The data includes the position data of the wafer stage (500); The first compensator in the object irradiation unit (100) is configured to move or rotate the scanning spot position (5) of the plurality of primary charged particle beamlets (3) on the wafer surface (25); A second compensator in the projection system (205) configured to compensate for displacement or rotation of the scanning spot positions (5) of the plurality of primary charged particle beamlets (3) and maintain the image detector ( The spot positions (15) of the plurality of secondary electron beamlets (9) on 207) are constant; A control unit (800) is configured to generate a first set of control signals Cp from a plurality of sensor data for capturing digital images of the first image patch (17.1) or the second image patch (17.2) During this period, a first compensator in the object irradiation unit (100) and a second compensator in the projection system (205) are controlled synchronously.

Item 13: The multiple-beam charged particle microscope (1) of item 12, wherein the control unit (800) is configured to provide the first set of control signals _Cp by calculating the first set of control signals _Cp One and the second compensator to compensate for positional or orientation changes of the wafer stage (500).

Item 14: The multiple-beam charged particle microscope (1) of any one of items 12 or 13, wherein the control unit (800) is configured to calculate the first set of control signals C _p and convert the first set of control signals C _p is provided to the first and the second compensator to compensate for positional variations of the line of sight ( 53 ) of the object illumination unit ( 100 ).

Item 15: The multiple-beam charged particle microscope (1) of any one of items 12 to 14, wherein the control unit (800) is configured to convert the first set of control signals C _p by calculating the first set of control signals _Cp is provided to the first and the second compensators to compensate for positional or orientation changes of the wafer stage (500) and positional changes of the line of sight (53) of the object irradiation unit (100).

Item 16: The multiple-beam charged particle microscope (1) of any one of items 12 to 15, wherein the control unit (800) is configured to convert the first set of control signals by calculating the first set of control signals C _p C _p is provided to the first and the second compensator to compensate for the wafer stage ( 500 ) during the capture of digital images of the first image patch ( 17.1 ) or the second image patch ( 17.2 ). Moving speed.

Item 17: A method of inspecting wafers using multiple beam charged particle microscopy, the steps are as follows: the first image capturing step of the first image patch during the first time interval Ts1; movement of the wafer stage from the position of the first image patch to the second image patch during the time interval Tr, and a second image capturing step of the second image patch during the second time interval Ts2, whereby, During a first time interval Ts1, at least a first error amplitude is calculated from the plurality of sensor signals, During the first time interval Ts1, the predicted first error amplitude develops at least through the moving time interval Tr and the second time interval Ts2, And, at least during the moving time interval Tr, a control signal is provided to the control unit of the multiple beam charged particle microscope for keeping the predicted development of the error amplitude during this second time interval Ts2 below a predetermined threshold.

Item 18: The method of item 17, wherein the prediction of the development of the first error amplitude is generated according to a prediction model or extrapolation.

Item 19: The method of item 17 or 18, wherein the first error amplitude represents at least one of line-of-sight displacement, wafer stage displacement, wafer stage rotation, line-of-sight rotation, magnification error, focus error, astigmatism error, or distortion error .

Item 20: The method of any one of items 17 to 19, wherein the control signal is provided to a control unit of the multiple-beam charged particle microscope for controlling a wafer stage, a first deflection unit, a second deflection unit, A component of at least one of the fast compensator of the multiple beamlet generation unit or the fast compensator of the detection unit.

Item 21: A method of operating a multiple beam charged particle microscope with a control unit, the method comprising a series of operations during image acquisition of a series of image patches containing a first image patch and a second subsequent image patch steps, which include: expanding the data stream forming the plurality of sensor data into a set of error amplitudes; capture a set of drift control signals and a set of dynamic control signals, and providing the set of drift control signals to a slow acting compensator; and The set of drift control signals are provided to the fast acting compensator.

Item 22: The method of Item 21, wherein the step of capturing the set of drift control signals and the set of dynamic control signals is performed during a time interval Ts1 of image capturing of the first image patch; and combining the set of drift control signals The step provided to the slow acting compensator is performed during the time interval Tr during which the substrate is moved by using the substrate stage from the first image patch to the second image patch.

Item 23: The method of item 21 or 22, wherein the step of providing the set of dynamic control signals to the fast motion compensator is performed within a time interval Ts1.

Item 24: The method of item 22 or 23, wherein the step of providing the set of dynamic control signals to the fast motion compensator is further performed within the image scanning time interval Ts2 of the second image patch.

Item 25: The method of any one of items 21 to 24, further comprising the step of predicting the temporal development of at least one error amplitude.

Item 26: The method of item 25, comprising predicting at least one slowly varying drift in error amplitude and predicting at least one rapidly varying dynamic change in error amplitude.

Item 27: A non-transitory computer-readable medium comprising a set of instructions executable by one or more processors of a device to cause the device to perform a method, wherein the device includes a source of charged particles , to generate a plurality of primary charged particle sub-beams, and the method includes: determining the lateral displacement of the stage, wherein the stage is movable in at least one of the X-Y axes; determining the lateral displacement of the line of sight of an object illuminating unit; and The controller is instructed to apply a first signal to deflect the plurality of primary charged particle beamlets incident on the sample to at least partially compensate for the lateral displacement. The second group of projects

Item 1: A multiple beam charged particle beam system comprising: a movable stage configured to hold a sample; an object irradiation unit configured to irradiate the surface of the sample with a plurality of foci of a plurality of primary charged particle sub-beams; a charged particle beam generator configured to generate a plurality of primary charged particle sub-beams from a charged particle source; a stage sensor configured to determine lateral displacement or rotation of the stage; an image sensor configured to determine the lateral displacement of the line of sight of the object illumination unit; and a control unit configured to generate and apply at least one additional voltage signal to a first beam deflector in the object illumination unit configured to generate a plurality of primary charged particles during use Additional displacement or rotation of the beam to at least partially compensate for the difference between the lateral displacement of the line of sight and the lateral displacement or rotation of the stage.

Item 2: The system of item 1, wherein the control unit is further configured to calculate the difference between the current position of the stage and the target position of the stage during scanning of the plurality of primary charged particle beamlets on the sample surface Correspondingly, the stage is laterally displaced or rotated.

Item 3: The system of item 1 or 2, wherein the control unit is further configured to calculate the difference between the current position of the line of sight and the target position of the line of sight during scanning of the plurality of primary charged particle beamlets on the sample surface Correspondingly, the line of sight is displaced laterally.

Item 4: The system of item 2 or 3, wherein the control unit and the first beam deflector are further configured to dynamically adjust at least one driving voltage signal during the scanning of the primary charged particle beam on the sample.

Item 5: The system of any one of items 1 to 4, further comprising a secondary beam deflector within the secondary electron beam path configured to at least partially compensate for the plurality of primary charged particle electrons originating during scanning Additional displacement or rotation of the plurality of secondary electron beamlets at the beam spot position of the beam.

Item 6: The system of any one of items 1 to 5, wherein the control unit further includes a stage motion controller, wherein the stage motion controller includes a plurality of motors configured to be independently controlled by a control signal.

Item 7: The system of any one of items 1 to 6, wherein the control unit includes a processor configured to derive the plurality of error vector amplitudes based on the plurality of sensor data, and to derive the plurality of error vector amplitudes from the plurality of error vectors At least one of the plurality of control signals is extracted from the amplitude.

Item 8: A method for irradiating a sample placed on a stage in a multiple beam charged particle beam system, the method comprising: generating a plurality of primary charged particle sub-beams from a charged particle source; determine the lateral displacement or rotation of the stage, wherein the stage is movable in the x-y plane; and determining the line of sight of the multiple beam charged particle system; Determine a displacement vector according to the lateral displacement or rotation of the stage and the line-of-sight position; applying at least one additional voltage signal to the beam deflector in the primary charged particle beam path for generating, during use, additional displacement or rotation of the plurality of primary charged particle beamlets for at least partially compensating for corresponding to The displacement vector of the lateral displacement or rotation of the stage relative to the line-of-sight position.

Item 9: The method of item 8, wherein the lateral displacement or rotation of the stage corresponds to the difference between the current position of the stage and the target position of the stage, and wherein the rotational displacement is between the plurality of primary charged particles The beamlets change during scanning on the sample stage.

Item 10: The method of any one of items 8 to 9, further comprising dynamically adjusting at least one of the voltage signals during the scanning of the primary charged particle beams on the sample.

Item 11: The method of any one of items 8 to 10, further comprising: supplying at least a second additional voltage signal to the beam deflector in the secondary electron beam path for at least partially compensating for a plurality of secondary electron beam spot positions resulting from a plurality of primary charged particle sub-beams during scanning Additional displacement or rotation of the electron beam.

Item 12: The method of any one of items 8 to 11, further comprising supplying a control signal to a stage motion controller, wherein the stage motion controller includes a plurality of motor.

Item 13: The method of any one of items 8 to 12, further comprising: A plurality of error vector amplitudes are derived based on the plurality of sensor data, and at least one of the plurality of control signals is extracted from the plurality of error vector amplitudes. The third group of projects

Item 1: A multiple beam charged particle microscope (1) for wafer inspection comprising: a charged particle multiple beamlet generator (300) configured to generate a plurality of primary charged particle beamlets (3) in a grating configuration (41); An object irradiation unit (100) configured for scanning a wafer surface (25) arranged in an object plane (101) using a plurality of primary charged particle beamlets (3) for illuminating a plurality of primary charged particle beams (3) At the scanning spot position (5) of the sub-beam (3), a plurality of secondary electron sub-beams (9) emitted from the wafer surface (25) are generated; a detection unit (200) having a projection system (205) and an image sensor (207) configured to image a plurality of secondary electron beamlets (9) on the image sensor (207), and configured to capture a digital image of the first image patch (17.1) of the wafer surface (25); a wafer stage (500) having a stage position sensor (520) configured to position and maintain the wafer surface (25) in the object plane (101) of the object illumination unit (100) during use; A first compensator (132, 110) in the object irradiation unit (100) configured to additionally displace or rotate the plurality of primary charged particle beamlets (3) on the wafer surface (25) Scan spot position (5), a second compensator (232, 222) in the projection system (205) configured to compensate for additional displacement or rotation of the scanning spot positions (5) of the plurality of primary charged particle beamlets (3) during use , and maintain the spot position (15) of the plurality of secondary electron beamlets (9) on the image detector (207) constant; and A control unit (800) configured to utilize at least the first compensator (132, 110) and the second compensator (232, 222) to compensate for the wafer surface caused by movement of the wafer stage (500) (25) displacement.

Item 2: The multi-beam charged particle microscope (1) of item 1, wherein the first compensator (132, 110) comprises an electrostatic lens, an electrostatic deflector, an electrostatic astigmatism, an electrostatic microlens array, an electrostatic astigmatism one of an array or an array of electrostatic deflectors.

Item 3: The multiple-beam charged particle microscope (1) according to any one of items 1 or 2, wherein the control unit (800) is configured to generate a first set of control signals _Cp for capturing the first image spot During the digital imaging of block (17.1), the first compensator (132, 110) in the object illumination unit (100) and the second compensator (232) in the projection system (205) are controlled synchronously.

Item 4: The multiple-beam charged particle microscope (1) according to any one of items 1 to 3, further comprising a third compensator (330, 332) in the charged-particle multiple sub-beam generator (300), which The scanning spot position (5) of the plurality of primary charged particle beamlets (3) on the wafer surface (25) is configured for additional displacement or rotation.

Item 5: The multiple-beam charged particle microscope (1) of item 4, wherein the control unit (800) is configured to generate a first set of control signals _Cp for capturing the digital bits of the first image patch (17.1) During imaging, the first compensator (132, 110) in the object irradiation unit (100), the second compensator (232, 222) in the projection system (205) or the charged particle multiple sub-beam generator are controlled synchronously The third compensator (330, 332) in (300).

Item 6: The multiple-beam charged particle microscope (1) according to any one of items 1 to 5, further comprising a plurality of detectors including the stage position sensor (520) and the image sensor (207) a sensor configured to generate a plurality of sensor data during use.

Item 7: The multiple beam charged particle microscope (1) of item 6, wherein the control unit (800) is configured to deduce from the plurality of sensor data for the first compensation in the object illumination unit (100) A drive signal of the transducers (132, 110) to achieve additional displacement of the scanning spot position (5) of the primary charged particle beamlets (3) in synchronization with the displacement of the wafer surface (25).

Item 8: The multiple beam charged particle microscope (1) of item 7, wherein the additional displacement includes rotation of the grating configuration (41) of the plurality of primary charged particle beamlets (3).

Item 9: The multiple beam charged particle microscope (1) of any one of items 6 to 8, wherein the control unit (800) is configured to pass the second compensator (232, 222) in the projection system (205) , compensating for additional displacement of the spot position (5) on the displaced wafer surface (25), wherein the second compensator (232, 222) in the projection system (205) is configured to be compatible with the object illumination unit (100) The first compensators (132, 110) operate synchronously in the image detector (207) so that the spot positions of the plurality of secondary electron beamlets (9) on the image detector (207) remain constant.

Item 10: The multiple-beam charged particle microscope (1) of any of the preceding items, wherein the first compensator in the object irradiation unit (100) is the first deflection system (110), and wherein the control unit (800) configured to provide the first deflection system (110) by computing and providing to the first deflection system (110) a control signal for additional displacement or rotation of the scanning spot position (5) of the plurality of primary charged particle beamlets (3), To compensate for the displacement or rotation of the wafer stage (500) relative to the sight line (53) of the object irradiation unit (100).

Item 11: The multiple beam charged particle microscope (1) of any preceding item, wherein the second compensator of the projection system (205) is the second deflection system (222), and wherein the control unit ( 800) is configured to compensate for the scanning spot position (5) of the plurality of primary charged particle sub-beams (3) on the displaced wafer surface ( 25) on the additional displacement or rotation.

Item 12: The multiple beam charged particle microscope (1) of any of the preceding items, comprising another compensator of the charged particle multiple sub-beam generator (300), another compensation of the detection unit (200) at least one of the compensator or another compensator of the object illumination unit (100).

Item 13: The multiple beam charged particle microscope (1) of any preceding item, wherein the control unit (800) includes a sensor data analysis system (818) configured to analyze a plurality of sensor data, and computes the set of K amplitudes _Ak of the K error vectors during use.

Item 14: The multiple-beam charged particle microscope (1) of item 13, wherein the control unit (800) further includes an image data acquisition unit (810) configured to capture data from the image sensor (207) during use ) to, for example, less than 10% of the image sensor data, preferably less than 2% of the image sensor data portion, and provide the image sensor data portion to the sensor data analysis system (818).

Item 15: The multiple beam charged particle microscope (1) of item 14, wherein the image data acquisition unit (810) is configured to capture images from the image sensor (207) at a reduced sampling rate during use The sensor data is reduced to an image sensor data portion that includes digital image data of a plurality of secondary electron beamlets.

Item 16: The multiple-beam charged particle microscope (1) of item 14, wherein the image data acquisition unit (810) is configured to reduce image sensor data from the image sensor (207) during use to The image sensor data portion includes the digital image data in the reduced secondary electron beamlet set.

Item 17: The multiple beam charged particle microscope (1) of any one of items 13 to 16, wherein the sensor data analysis system (818) is configured to predict the difference of at least one amplitude An of the set of amplitudes Ak of the error vector time develops.

Item 18: The multiple-beam charged particle microscope (1) of any one of items 13 to 17, wherein the control unit (800) further comprises a control operation processor (840) for determining the amplitude _Ak from the error vector to calculate the first set of control signals C _p .

Item 19: The multiple beam charged particle microscope (1) of any one of items 13 to 18, wherein the sensor data analysis system (818) is configured to derive a sensor of length L from the plurality of sensor data The detector data vector DV, where L >= K.

Item 20: The multiple beam charged particle microscope (1) of any one of items 4 to 19, wherein the control unit (800) is configured to calculate and provide at least one of the control signals of the first set of control signals _Cp The third compensator (330, 332) is given to cause a rotation of the grating configuration (41) of the primary charged particle beamlets (3) to compensate for the rotation of the wafer stage (500).

Item 21: The multiple-beam charged particle microscope (1) of any one of items 1 to 20, wherein the control unit (800) is further configured to generate a control signal for passing the wafer stage (500) to the The wafer surface (25) is moved to the second center position of the second image patch (17.2) in the object plane (101), and the image capture of the digital image of the second image patch (17.2) is performed.

Item 22: The multiple-beam charged particle microscope (1) of item 21, wherein the control unit (800) is further configured to calculate a second set of P control signals _Cp from the plurality of sensor data for use on the wafer stage (500) Control any of the compensators during the time interval Tr when moving to the second center position of the second image patch (17.2).

Item 23: The multiple beam charged particle microscope (1) of any one of items 21 to 22, wherein the control unit (800) is further configured to calculate the image of the second image patch (17.2) during the time interval Tr capture start time and start image capture of the second image patch (17.2) during the deceleration time interval Td of the wafer stage (500), and wherein the control unit (800) is further configured to An offset signal of the predicted offset position of the wafer stage (500) during interval Td is provided to the first and second compensators. Fourth group of projects

Item 1: A multiple beam charged particle beam system comprising: a stage configured to hold the sample and movable in at least one of the X-Y and Z axes; a position sensing system configured to determine lateral and vertical displacement or rotation of the stage; and a controller configured to apply a first signal to deflect the plurality of primary charged particle beams incident on the sample to at least partially compensate for lateral displacement of the stage; and to apply a second signal to deflect the plurality of secondary electron beams beam to at least partially compensate for the displacement of the plurality of secondary electron beamlets originating from the positions of the deflected primary charged particle beamlets on the sample.

Item 2: The system of item 1, wherein the first signal comprises an electrical signal that affects how the plurality of primary charged particle beamlets are deflected in at least one of the X-Y axes.

Item 3: The system of item 2, wherein the electrical drive signal comprises a signal having a frequency bandwidth ranging from 0.1 kHz to 10 kHz.

Item 4: The system of any one of items 1 to 3, wherein the lateral displacement corresponds to a difference in at least one of the X-Y axes between the current position of the stage and the target position of the stage.

Item 5: The system of any one of items 1 to 4, wherein the controller is further configured to dynamically adjust at least one of the first signal or the second signal during scanning of the plurality of primary charged particle sub-beams on the sample .

Item 6: The system of any one of items 1 to 5, further comprising a stage motion controller, wherein the stage motion controller includes a plurality of motors configured to be independently controlled by a third signal.

Item 7: The system of item 6, wherein each of the plurality of motors is independently controlled to adjust the tilt of the stage so that the stage is substantially perpendicular to the optical axis of the primary charged particle beam.

Item 8: The system of any one of items 6 or 7, wherein the plurality of motors comprise at least one of piezoelectric motors, piezoelectric actuators, or ultrasonic piezoelectric motors.

Item 9: The system of any one of items 1 to 8, further comprising a first component configured to form a plurality of error vector amplitudes based on the plurality of sensor signals; and a second component configured from At least one of the plurality of control signals is extracted from the plurality of error vector amplitudes.

Item 10: The system of item 9, wherein the first component is configured to form a plurality of error vector amplitudes based on the lateral displacement of the stage and the lateral displacement of the actual position of the line of sight of the multiple beam charged particle beam system.

Item 11: The system of any of items 9 or 10, wherein the extraction of at least one of the plurality of control signals is based on a prediction model of the plurality of error vector amplitudes.

Item 12: The system of any of items 9 or 11, wherein the acquisition of at least one of the plurality of control signals is based on a predictive model of the actuation output of the stage.

Item 13: The system of any one of items 1 to 12, wherein the position sensing system uses any one of a laser interferometer, a capacitive sensor, a confocal sensor array, a grating interferometer, or a combination thereof, To determine the lateral and vertical displacement and rotation of the stage. Fifth group of projects

Item 1: A method for irradiating a sample placed on a stage in a multiple beam charged particle beam system, the method comprising: generating a plurality of primary charged particle sub-beams from a charged particle source; determining lateral displacement and rotation of the stage, wherein the stage is movable in at least one of the X-Y and Z axes; applying a first signal to deflect a plurality of primary charged particle beamlets incident on the sample to at least partially compensate for lateral displacement or rotation of the stage; and A second signal is applied to deflect the plurality of secondary electron beamlets to at least partially compensate for displacement of the plurality of secondary electron beamlets originating from the position of the deflected primary charged particle beamlets on the sample.

Item 2: The method of item 1, wherein the first signal comprises an electrical signal that affects how the primary charged particle beam is deflected in at least one of the X-Y axes.

Item 3: The method of any one of items 1 to 2, wherein the lateral displacement corresponds to a difference in at least one of the X-Y axes between the current position of the stage and the target position of the stage.

Item 4: The method of any one of Items 1 to 3, further comprising dynamically adjusting at least one of the first signal or the second signal during scanning of the plurality of primary charged particle beams on the sample.

Item 5: The method of any one of Items 1 to 4, further comprising: The third signal is applied to a stage motion controller, wherein the stage motion controller includes a plurality of motors configured to be independently controlled by the third signal.

Item 6: The method of any one of items 1 to 5, further comprising: A plurality of error vector amplitudes are derived based on the plurality of sensor data, and at least one of the plurality of control signals is extracted from the plurality of error vector amplitudes.

Item 7: The method of item 6, further comprising a temporal behavior prediction model based on the amplitudes of the plurality of error vectors to predict at least one of the control signals.

Item 8: The method of any one of items 6 to 7, further comprising predicting at least one of the plurality of control signals based on the prediction model of the actuation output of the stage. The sixth group of projects

Item 1: A wafer inspection method using a multiple beam charged particle microscope (1), the microscope having a plurality of detectors, the detectors including an image sensor (207) and a stage position sensing and having a set of compensators, the set of compensators including at least first and second deflection systems (110, 222), the method comprising: positioning the crystal with the line of sight of the multiple beam charged particle microscope (1) round wafer surface (25) and aligned with the position of the local wafer coordinate system (551); performing an image capture to capture the digits of the first image patch (17.1) of the wafer surface (25) image; collecting a plurality of sensor data from the plurality of detectors; deriving a set of _K error amplitudes _Ak from the plurality of sensor data; deriving a first set of control signals _Cp ; the first set of control signals _Cp is supplied to a set of compensators during the step of image capture.

Item 2: The wafer inspection method using the multiple-beam charged particle microscope (1) as in Item 1, further including: A sensor data vector DV of length L is derived from the plurality of sensor data, where L >= K.

Item 3: The wafer inspection method using the multiple-beam charged particle microscope (1) according to any one of Items 1 to 2, further comprising: A time development of at least one amplitude An of a set of error vector amplitudes Ak is derived.

Item 4: The wafer inspection method using a multiple-beam charged particle microscope (1) according to any one of items 1 to 3, further comprising: by providing a control signal C _p to the first and the second deflection unit ( 110, 222) to compensate for changes in the position or orientation of the wafer stage (500).

Item 5: The wafer inspection method using the multiple-beam charged particle microscope (1) according to any one of Items 1 to 4, further comprising: deriving a second set of control signals _Cp from the set of error amplitudes _Ak , and provide the second set of control signals during step a) of positioning and aligning the wafer surface (25) of the wafer. Seventh group of projects

Item 1: A method of operation of a multiple beam charged particle microscope (1) configured for wafer inspection, comprising: define a set of image qualities and a set of predetermined, normalized error vectors describing deviations from the set of image qualities; determine a set of thresholds for the amplitude of the set or normalized error vector; Select a set of compensators for multiple beam charged particle microscopes; According to the linear disturbance model, by changing at least one driving signal of each compensator in the set of compensators, to determine the sensitivity matrix; deriving a set of normalized drive signals for compensating for each of the set of normalized error vectors; The normalization error vector, the critical group and the normalization error vector are stored in the memory of the multiple beam charged particle microscope control unit.

Item 2: The method of operation of the multiple-beam charged particle microscope (1) of item 1, wherein the set of compensators includes the multiple-beam charged particle microscope (1) for scanning and deflecting a plurality of primary charged particles (3) a first deflection unit (110), and a second deflection unit (222) for scanning and deflecting a plurality of secondary electron sub-beams (9) generated during use of the multiple beam charged particle microscope (1). Eighth group of projects

Item 1: A method of operating a multiple beam charged particle microscope (1), comprising: the step of receiving, during use, a plurality of sensor data from a plurality of sensors of the multiple beam charged particle microscope (1) and forming a sensor data vector; the step of expanding the sensor data vector within a set of normalized error vectors stored in control unit memory, and determining the actual amplitude of a set of normalized error vectors from the sensor data vector; the step of comparing the set of actual amplitudes with a set of thresholds stored in the control unit memory; the step of deriving a set of control signals from the set of actual amplitudes based on a comparison of the set of actual amplitudes with a set of stored thresholds; The step of deriving a set of actual drive signals from a set of normalized drive signals stored in the control unit memory from the set of control signals; The set of actual drive signals is provided to a set of compensators of the multiple beam charged particle microscope (1), thereby reducing the set of actual amplitudes of the set of normalized error vectors to steps below the set threshold.

Item 2: The method of operation of the multiple-beam charged particle microscope (1) of item 1, wherein the plurality of sensor data are included in the data for maintaining or moving the crystal during detection using the multiple-beam charged particle microscope (1). At least one of the actual position of the wafer stage ( 500 ) and the actual velocity of the position or velocity information of the circle.

Item 3: The method of operation of the multiple beam charged particle microscope (1) of item 1, wherein the plurality of sensor data includes the line of sight (52) during wafer inspection using the multiple beam charged particle microscope (1) at least one of the actual locations.

Item 4: The method of operating the multiple-beam charged particle microscope (1) according to any one of Items 1 to 3, wherein the steps are repeated at least twice, at least ten times, preferably each time during image plaque capture while scanning.

Item 5: The method of operating the multiple beam charged particle microscope (1) according to any one of items 1 to 4, further comprising, during wafer inspection, according to the expected development of the multiple beam charged particle microscope within a predicted time interval , to predict the step of developing a subset of amplitudes for at least a subset of the actual amplitudes of the set.

Item 6: The method of operation of the multiple beam charged particle microscope (1) according to any one of items 1 to 5, further comprising, during use, recording at least a subset of the set of actual amplitudes of the multiple beam charged particle microscope , for the step of generating a subset histories of actual amplitudes for the set.

Item 7: The method of operating the multiple beam charged particle microscope (1) of any one of Items 1 to 6, further comprising deriving a set of predictive control signals from the set of developed amplitudes during wafer inspection and deriving from the set of predictive control signals The step of deriving a set of predicted drive signals from the set of predictive control signals, and the step of providing the set of predicted drive signals to the set of compensators in a time-sequential manner during wafer inspection, results in a multi-beam charged particle microscope in predicting During operation within the time interval, a subset of the actual amplitudes are reduced below the set of thresholds.

Item 8: A multiple beam charged particle microscope having a control unit (800) and having installed software code, configured for applying any of the methods of any of items 1-7. ninth group of projects

Item 1: A method of focusing a plurality of primary charged particle sub-beams on a sample, the method comprising: Using a plurality of primary charged particle sub-beams to irradiate the sample placed on the stage of the multi-beam charged particle beam system, and to form a plurality of foci on the surface of the sample; adjusting the position and rotation of the plurality of focal points of the plurality of charged particle sub-beams relative to the sample using at least a first component of the multi-beam charged particle system; and scanning the focal points of the plurality of primary charged particle sub-beams with reference to the sample along a plurality of predetermined primary scanning beam paths using a second component of the multiple beam charged particle system; and Using the first, the second or a third component, a predetermined scanning beam path with respect to the sample is dynamically manipulated.

Item 2: The method of item 1, wherein the method includes adding at least a first deflection voltage to a first scan voltage for scanning a focal point of the plurality of primary charged particle beamlets by using the second component.

Item 3: The method of item 1 or 2, which further includes: generating a plurality of primary charged particle beamlets using a charged particle multiple beamlet generator; and The position and rotation of the plurality of focal points of the plurality of charged particle sub-beams are adjusted or dynamically manipulated with reference to the sample using a component of the charged particle multiple sub-beam generator.

Item 4: The method of any one of Items 1 to 3, further comprising: generating and collecting a plurality of secondary electron beamlets originating from the sample surface at a plurality of foci of a plurality of primary charged particle beamlets; Using the fourth component of the projection system in the multiple-beam charged particle system, scanning a plurality of secondary electron sub-beams along a predetermined secondary electron beam path such that the focal point of the plurality of secondary electron sub-beams is at the image sensing at the constant position of the device; The predetermined secondary electron beam path is dynamically steered with reference to the image sensor using the fourth or fifth component of the projection system in the multiple beam charged particle system.

Item 5: The method of item 4, wherein the method includes adding at least a second deflection voltage to a second scan voltage for scanning the plurality of secondary charged particle beamlets by using the fourth component.

Item 6: The method of any one of items 1 to 5, further comprising: determine the current position of the stage; and The lateral displacement or rotation of the stage is determined based on the difference between the current position of the stage and the target position of the stage.

Item 7: The method of item 6, which further includes: determining the first deflection voltage for compensating for lateral displacement or rotation of the stage, The first deflection voltage is applied to at least the first, the second or the third component for dynamically steering a predetermined first scanning beam path with reference to the sample.

Item 8: The method of any one of Items 6 or 7, further comprising: determine the second deflection voltage, The second deflection voltage is applied to at least the fourth or fifth component for dynamically steering a predetermined secondary electron beam path with reference to the image sensor. tenth group of projects

Item 1: A multiple beam charged particle beam system comprising: an object irradiation unit configured to irradiate the surface of the sample with a plurality of foci of a plurality of primary charged particle sub-beams; a first component of the object irradiation unit configured to adjust the position and rotation of the plurality of focal points of the plurality of charged particle sub-beams relative to the sample; and a second component of the object irradiation unit configured to scan a focal point of a plurality of primary charged particle beamlets with reference to the sample along a plurality of predetermined primary scanning beam paths; and A third component configured to dynamically steer the predetermined scanning beam path with respect to the sample position.

Item 2: The multiple beam charged particle beam system of item 1, wherein the third component is the first component.

Item 3: The multiple beam charged particle beam system of item 2, wherein the third component is the second component.

Item 4: The multiple-beam charged particle beam system of item 3, further comprising a control unit configured to add at least a first deflection voltage configured to dynamically steer the predetermined scanning beam path to a supply to the configuration is a first scan voltage of the second component for scanning the focal points of the plurality of primary charged particle sub-beams.

Item 5: The multiple beam charged particle beam system of any one of items 1 to 4, further comprising a charged particle multiple sub-beam generator configured to generate a plurality of primary charged particle beamlets.

Item 6: The multi-beam charged particle beam system of any one of items 1 to 5, further comprising a control unit configured to use the first component to adjust the line of sight of the object irradiation unit during use.

Item 7: The multiple-beam charged particle beam system of any one of items 1 to 6, further comprising: a projection system configured to collect and image a plurality of secondary electron beamlets originating from the sample surface at a plurality of foci of a plurality of primary charged particle beamlets; an image sensor for detecting a plurality of focal spots of a plurality of secondary electron beamlets; A fourth component of the projection system in a multiple beam charged particle system configured to scan a plurality of secondary electron sub-beams along a predetermined secondary electron beam path such that the plurality of secondary electron sub-beams are The focal point is at a constant position at the image sensor; A fifth component of the projection system in a multiple beam charged particle system configured to dynamically steer a predetermined secondary electron beam path with reference to the image sensor.

Item 8: The multiple beam charged particle beam system of item 7, wherein the fifth component is the fourth component.

Item 9: The multiple beam charged particle beam system of item 8, wherein the control unit is further configured to add at least a second deflection voltage configured to dynamically steer the predetermined secondary electron beam path to the A second scan voltage for scanning the fourth component of the plurality of secondary charged particle sub-beams.

Item 10: The multiple beam charged particle beam system of any one of items 1 to 9, further comprising a stage sensor configured to determine lateral displacement or rotation of the stage.

Item 11: The multiple beam charged particle beam system of item 10, wherein the control unit is further configured to derive the first and the second deflection voltages from lateral displacement or rotation provided by the stage sensor .

Item 12: The system of any one of items 1 to 11, wherein the first component is located upstream of the second component. Eleventh group of projects

Item 1: A method of performing wafer inspection using a multiple beam charged particle beam apparatus, the method comprising: irradiating the sample placed on the stage with a plurality of primary charged particle electron beams; Static adjustment of the focus of a plurality of primary charged particle beamlets; Dynamic manipulation of the focus of a plurality of primary charged particle beamlets.

Item 2: The method of item 1, which further includes: determining the slow change of the multiple beam charged particle beam device, comprising determining the slow change of the object irradiation unit and detecting the drift of the stage configured to maintain the sample; determining a first drift compensation signal to compensate for slow changes; and The first drift compensation signal is applied to at least one component of the object illumination unit to perform a static adjustment of the focal points of a plurality of primary charged particle sub-beams.

Item 3: The method of item 2, wherein determining the slow change of the object illumination unit comprises determining the slow change of the line of sight of the object illumination unit.

Item 4: The method of any one of Items 1 to 3, further comprising: determining the dynamics of the multiple beam charged particle beam apparatus, comprising determining the dynamics of the object irradiation unit and detecting vibrations of the stage configured to maintain the sample; determining a first dynamic compensation signal to compensate for dynamic changes; and The first dynamic compensation signal is applied to at least one component of the object illumination unit to perform dynamic manipulation of the focal points of a plurality of primary charged particle sub-beams.

Item 5: The method of item 4, wherein determining the dynamic change of the object illumination unit comprises determining the dynamic change of the line of sight of the object illumination unit.

Item 6: The method of any one of items 2 to 5, further comprising: determining a second drift compensation signal to compensate for slow changes; and A second drift compensation signal is applied to at least one component of the projection unit to compensate for static adjustments of the plurality of secondary electron beamlets resulting from the adjusted focus of the plurality of primary charged particle beamlets.

Item 7: The method of any one of items 4 to 6, further comprising: determining a second dynamic compensation signal to compensate for dynamic changes; and A second dynamic compensation signal is applied to at least one component of the projection unit to compensate for dynamic steering of the plurality of secondary electron beamlets resulting from dynamically steered focal points of the plurality of primary charged particle beamlets.

Item 8: The method of any one of items 1 to 7, wherein the determination of the first and second drift compensation signals is based on a predictive model of the temporal behavior of the multiple beam charged particle beam device.

Item 9: The method of item 8, wherein the determination of the first or second drift compensation signal and the first or second dynamic compensation signal is based on a frequency analysis of the temporal behavior of the multiple beam charged particle beam device.

Item 10: The method of any one of items 1 to 9, further comprising receiving a plurality of sensor signals including sensor signals from the stage position sensor and the image sensor.

Item 11: The method of item 10, further comprising determining, using a control unit, the drift and motion compensation signals based on the plurality of sensor signals received.

Item 12: The method of any one of items 1 to 11, further comprising: using the processor of the control unit to evaluate a predictive model of the temporal behavior of the multiple beam charged particle beam device; and The drift and dynamic compensation signals are determined based on the predictive model using a control unit.

Item 13: The method of item 12, wherein the evaluation of the predictive model includes frequency analysis, low-pass filtering, and polynomial approximation.

Item 14: The method of item 12 or 13, further comprising synchronizing the drift and motion compensation signal with the prediction model using at least one delay line.

Item 15: The method of any one of Items 1 to 14, further comprising: generating a beam of deflection signals based on the dynamic compensation signal; modifying a beam of scanning signals with the beam deflection signal; and The modified beam scanning signal is provided to a scanning beam deflection unit. Twelfth group of projects

Item 1: A multiple beam charged particle microscope (1) for wafer inspection, comprising: a charged particle multiple beamlet generator (300) for generating a plurality of primary charged particle beamlets (3), An object irradiation unit (100) comprising a first deflection system (110) for scanning a wafer surface (25) arranged in an object plane (101) with a plurality of primary charged particle beamlets (3) for scanning with a plurality of primary charged particle beamlets (3) generating a plurality of secondary electron beamlets (9) emitted from the wafer surface (25) at spot positions (5) of a plurality of primary charged particle beamlets (3), having a projection system (205) ), a second deflection system (222) and a detection unit (200) of an image sensor (207) for imaging a plurality of secondary electron beamlets (9) on the image sensor (207) ) and captures a digital image of the first image patch (17.1) of the wafer surface (25) during use, a wafer stage (500) having a stage position sensor (520) for use in The wafer surface (25) is positioned and maintained in the object plane (101) during the acquisition of the digital image of the first image patch (17.1). a plurality of detectors including the stage position sensor (520) and the image sensor (207), the detectors configured to generate a plurality of sensor data during use, the sensor The data include position data of the wafer stage (500), a set of compensators, which at least include compensators in the object irradiation unit (100) and compensators in the projection system (205), a control unit (800), which configured to generate a first set of control signals _Cp from a plurality of sensor data to control the set of compensators during the capture of the digital image of the first image patch (17.1), wherein the control unit (800) is configured To compensate for the displacement of the wafer surface (25) caused by the movement of the wafer stage (500).

Item 2: The multiple-beam charged particle microscope (1) of item 1, wherein the control unit (800) is configured to provide the first set of control signals _Cp by calculating the first set of control signals _Cp A and the second compensator to compensate for the positional variation of the sight line (53) of the object illuminating unit (100).

Item 3: The multiple-beam charged particle microscope (1) of any one of items 1 or 2, wherein the control unit (800) is configured to calculate the first set of control signals C _p and convert the first set of control signals _Cp is provided to the first and the second compensators to compensate for positional or orientation changes of the wafer stage (500) and positional changes of the line of sight (53) of the object irradiation unit (100). Thirteenth group of projects

Item 1: A multiple beam charged particle microscope (1) for wafer inspection, comprising: a. a charged particle multiple beamlet generator (300) for generating a plurality of primary charged particle beamlets (3 ); b. an object irradiation unit (100) comprising a first deflection system (110) for scanning a wafer surface (25) arranged in the object plane (101) using a plurality of primary charged particle beamlets (3) ) for generating a plurality of secondary electron beamlets (9) emitted from the wafer surface (25); c. having a projection system (205), a second deflection system (222) and an image sensor a detection unit (200) of the detector (207) for imaging a plurality of secondary electron beams (9) on the image sensor (207) and capturing the wafer surface (207) during use 25) digital image of the first image patch (17.1); d. a wafer stage (500) having a stage position sensor (520) for capturing the digital image of the first image patch (17.1) positioning and maintaining the wafer surface (25) in the object plane (101) during imaging; e. a control unit (800); f. a plurality of detectors including the stage position sensor (520) and the image sensors (207) configured to generate a plurality of sensor data during use, the sensor data including position data of the wafer stage (500); g. a set of compensators , which includes at least the first and the second deflection system (110, 222), wherein the control unit (800) is configured to generate a first set of control signals _Cp from a plurality of sensor data for capturing the The set of compensators are controlled during digital imaging of the first image patch (17.1).

Item 2: The multiple-beam charged particle microscope (1) of item 1, wherein the set of compensators further comprises compensators (330, 332) of the charged-particle multiple sub-beam generator (300) and the detection unit (200) At least one of the compensators (230, 232).

Item 3: The multiple beam charged particle microscope (1) of any of items 1 or 2, wherein the control unit (800) includes a sensor data analysis system (818) configured to analyze during use A plurality of sensor data, and the set of K amplitudes _Ak of the K error vectors is calculated during use.

Item 4: The multiple-beam charged particle microscope (1) of item 3, wherein the control unit (800) further comprises an image data acquisition unit (810) configured to capture data from the image sensor (207) during use ) to, for example, less than 10% of the image sensor data, preferably less than 2% of the image sensor data fraction, and provide the image sensor data fraction to the sensor Device Data Analysis System (818).

Item 5: The multiple beam charged particle microscope (1) of any of items 3 or 4, wherein the sensor data analysis system (818) is configured to predict at least one amplitude of the set of amplitudes _Ak of the error vector _The time development of An.

Item 6: The multiple-beam charged particle microscope (1) according to any one of items 3 to 5, wherein the control unit (800) further comprises a control operation processor (840) for determining the amplitude _Ak of the error vector to calculate the first set of control signals C _p .

Item 7: The multiple beam charged particle microscope (1) of any one of items 3 to 6, wherein the sensor data analysis system (818) is configured to derive a sensor of length L from the plurality of sensor data The detector data vector DV, where L > K.

Item 8: The multiple-beam charged particle microscope (1) of any one of items 1 to 7, wherein the control unit (800) is configured to convert the first set of control signals C _p by calculating at least one of the first set of control signals C p At least one of a set of control signals _Cp is provided to the first and second deflection units (110, 222) to compensate for positional or orientation changes of the wafer stage (500).

Item 9: The multiple beam charged particle microscope (1) of any one of items 1 to 8, wherein the control unit (800) is configured to convert the first set of control signals C _p by calculating at least one of the first set of control signals C p At least one of a set of control signals C _p is provided to the first and second deflection units ( 110 , 222 ) to compensate for changes in the position of the line of sight ( 53 ) of the object illumination unit ( 100 ).

Item 10: The multiple beam charged particle microscope (1) of any one of items 1 to 9, wherein the control unit (800) is configured to convert the first set of control signals C _p by calculating at least one of the first set of control signals C p At least one of a set of control signals C _p is provided to the first and the second deflection units ( 110 , 222 ) to compensate for changes in position or orientation of the wafer stage ( 500 ) and the object irradiation unit ( 100 ) The position of the line of sight (53) changes.

Item 11: The multiple-beam charged particle microscope (1) according to any one of items 1 to 10, wherein the charged-particle multiple sub-beam generator (300) further comprises a fast compensator (330), and the control unit (800 ) is configured to cause at least one of the plurality of primary charged particle beamlets by calculating at least one of the first set of control signals _Cp and providing at least one of the first set of control signals _Cp to a fast compensator (330). Rotate to compensate for the rotation of the wafer stage (500).

Item 12: The multiple beam charged particle microscope (1) of any one of items 1 to 11, wherein the control unit (800) is further configured to generate a third control signal for passing the wafer stage (500) The wafer surface (25) is moved to the second center position of the second image patch 17.2 in the object plane (101), and the digital image of the second image patch (17.2) is captured.

Item 13: The multiple-beam charged particle microscope (1) of item 12, wherein the control unit (800) is further configured to calculate a second set of P control signals _Cp from the plurality of sensor data for use on the wafer stage (500) Control the set of compensators during the time interval Tr when moving to the second center position of the second image patch (17.2).

Item 14: The multiple beam charged particle microscope (1) of any one of items 12 to 13, wherein the control unit (800) is further configured to calculate the image capture of the second image patch 17.2 during the time interval Tr start time, and start the image capture of the second image patch 17.2 during the deceleration time interval Td of the wafer stage (500), and wherein the control unit (800) is further configured to convert at least the wafer stage (500) ) one of the predicted offset positions during the time interval Td is provided to the first and second deflection yokes (110, 222) with an offset signal. Group 14 Projects

Item 1: A method of improving the throughput of a multiple beam charged particle microscope, comprising: generating a plurality of beam spots of a plurality of primary charged particle sub-beams on a sample surface having a grating configuration with a beam spacing d1; jointly scanning a plurality of primary charged particles along a predetermined scanning path; controlling the beam spacing d1 of a plurality of primary charged particle beams; Wherein the control includes compensating for changes in the beam spacing d1 by using a compensator for manipulating the position of the beam spot, thereby reducing an overlapping area.

Item 2: The method of item 1, wherein the controlling includes providing a control signal to a multi-beam multi-pole deflector device to dynamically control the positions of a plurality of beam spots on the sample surface with high precision, the high precision being 100 nm or less and 70 nm Below, even below 30 nm.

Item 3: The method of item 1 or 2, further comprising the step of sensing the focal position of the sample surface with a high-precision image sensor below 100 nm, below 70 nm or even below 30 nm.

Item 4: The method of any one of items 1 to 3, wherein the beam path d1 is about 10 μm.

A non-transitory computer-readable medium may be provided that stores a processor (eg, of control unit 800 or sensor data analysis system 818) to perform wafer inspection, wafer imaging, stage calibration, displacement error calibration, displacement Error compensation, manipulating the electromagnetic field associated with the sample, communicating with the image data acquisition unit 810, activating an acceleration sensor, or executing an algorithm to evaluate or predict the multiple beamlet charged particle microscopy system 1 including the sample stage 500 Instructions for performance and control operations of the multiple sub-beam charged particle system. Common forms of such non-transitory media include, for example, hard drives, solid state drives, any optical data storage media, random access memory (RAM), programmable read only memory (PROM), and erasable programmable read only memory (EPROM), FLASH-EPROM or any other flash memory, non-volatile random access memory (NVRAM), cache, scratchpad, any other memory wafer or storage cartridge.

The block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer hardware or software products according to the many exemplary embodiments of the present invention. Thus, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which may include one or more executable instructions to implement the specified logical function(s). It should be understood that, in some alternative implementations, the functions noted in the block diagrams may be performed out of the order noted in the figures. For example, two blocks shown in succession may in fact be executed concurrently or the order may be reversed, depending upon the functionality involved. Certain blocks can also be omitted. It will be understood that each block of the block diagrams, and combinations of blocks within the block diagrams, can be implemented using special purpose hardware systems that perform special functions or actions, or through combinations of special purpose hardware and computer instructions.

It is to be understood that the specific embodiments of the present invention are not limited to the precise constructions described above and illustrated in the accompanying drawings, and that various modifications and changes may be made without departing from the scope of the present invention. It should be understood that the present invention is not limited to these combinations of sub-items and that various modifications and changes or other combinations of sub-items may be made without departing from its scope. It should be understood that the present invention is not limited to a method or an apparatus, but will encompass any apparatus configured to operate according to any method or any method utilizing any of the apparatus elements and configurations described or combinations of subitems.

1: Multiple sub-beam charged particle microscopy system 3: Primary charged particle sub-beam, forming a plurality of primary charged particle sub-beams 5: Primary charged particle beam focus 7: Object or Wafer 9: Secondary electron sub-beam, forming a plurality of secondary electron sub-beams 11: Secondary electron beam path 13: Primary beam path 15: Secondary charged particles like spots or foci 17: Image Plaque 19: Overlap area 21: Image patch center position 25: Wafer Surface 27: Scanning Path of Primary Charged Particle Beam 29: Center of image subfield 31: Image subfield 33: The first detection part 35: The second detection part 37: Image subfield after scan rotation 39: Overlap area of subfield 31 41: Raster configuration 51: Image Coordinate System 53: Sight of the Multiple Beam Charged Particle Microscope 55: Displacement vector 59: Rotation vector components 61: Individual displacements like spots 100: Object irradiation unit 101: Object plane 102: Objective lens 103.1, 103.2: First and Second Field Lenses 105: Optical axis of multiple sub-beam charged particle microscopy systems 108: First beam intersection 110: First deflection system 130: Slow Compensator for Object Irradiation Unit 132: Fast Dynamic Compensator for Object Irradiation Unit 138: Object illumination unit sensor 200: Detection unit 205: Projection System 206: Electrostatic Lens 207: Image Sensor 208: Imaging Lens 209: Imaging Lenses 212: Second Intersection 214: Hole 216: Active Components 218: Third deflection system 220: Multi-Aperture Corrector 222: Second deflection system 230: Slow Compensator for Secondary Electron Beam Path 232: Fast compensator for detection unit 238: Secondary Electron Beam Path Sensor 300: Charged Particle Multiplex Beam Generator 301: Charged Particle Source 303: collimating lens 305: Primary Multiple Sub-Beamforming Unit 306: Active Multi-Well Plate Configuration 307: First Field Lens 308: Second Field Lens 309: Divergent Electron Beam 311: Focus of primary electron beam 321: Intermediate Image Plane 330: Slow compensator for multiple beamlet generators 332: Fast Compensator for Multiple Subbeam Generators 390: Beam Steering Array or Deflector Array 400: Beam splitter unit 420: Magnetic focusing lens 430: Slow compensator for beam splitter unit 500: Sample stage 503: Sample voltage supply 520: Stage position sensor 551: Local Wafer Coordinate System 601: Active Multi-Aperture Array 607: Conductive thread 681: Electrodes 685: Hole or Hole Array 800: Control Unit 810: Image data capture unit 812: Image stitching unit 814: Image data memory 818: Sensor Data Analysis System 820: Projection system control module 830: Primary beam path control module 840: Control Operations Processor 860: Deflection Control Module 880: Stage Control Module 901: Error amplitude critical 903: Error Amplitude Gradient 905: Error amplitude critical window 907: Error amplitude model function 909: Error Amplitude Gradient

More details will be disclosed below with reference to the accompanying drawings. thus showing: FIG. 1 is a diagram of a multiple beam charged particle microscope system according to an embodiment. FIG. 2 shows a first detection site and a second detection site including first and second image patches. Figure 3a is a sketch of the displaced and rotated image coordinate system relative to the local wafer coordinate system. Figure 3b is a sketch of a rotated image patch relative to the local wafer coordinate system rotation. Figure 4 is a graph of the slowly varying drift component of the error amplitude before (a) and after (b) compensation in accordance with the present invention. Figure 5 is a graph of the rapidly changing component or dynamic of error amplitude before (a) and after (b) compensation in accordance with the present invention. 6 is a block diagram of a multiple beam charged particle microscope system including a detailed view of a control unit 800 according to an embodiment of the present invention. 7 is a block diagram of a method of operation of a multiple beam charged particle microscope system for wafer inspection according to an embodiment of the present invention. Figure 8 is a diagram of an active multi-well plate.

5: Primary charged particle beam focus

17: Image patches, such as first or second image patches 17.1, 17.2

21: Image patch center position

27: Scanning Path of Primary Charged Particle Beam

29: Center of image subfield

31: Image subfield

37: Image subfield after scan rotation

41: Raster configuration

Claims (27)

A method of operating a multi-beam charged particle microscope (1) with high throughput and high resolution, comprising: A first image capture of a first image patch 17.1 in the first time interval Ts1 and the second image capture of the second image patch 17.2 in the second time interval Ts2; and a third time interval for moving a wafer stage (500) from a first center position (21.1) of the first image patch (17.1) to a second center position (21.2) of the second image patch 17.2 Tr, so that at least one of the first time interval Ts1 and the second time interval Ts2 has an overlap with the third time interval Tr. The method of operation of a multiple beam charged particle microscope (1) as claimed in claim 1, wherein the second image spot is started before the third time interval Tr ends, ie before the wafer stage (500) has come to a complete stop Second image capture of block 17.2. The operation method of the multi-beam charged particle microscope (1) of claim 1 or 2, wherein the third time interval Tr is before the end of the first time interval Ts1, that is, when an image of the first image patch 17.1 is captured Take the completion time before starting. The method of operation of a multi-beam charged particle microscope (1) according to any one of claims 1 to 3, further comprising calculating the third time interval Ts1 during the first time interval Ts1 of image capture of the first image patch 17.1 The start time of the time interval Tr such that the positional deviation between the first center position of the first image patch 17.1 and the line of sight (53) of the multiple beam charged particle microscope (1) or the moving speed of the wafer stage (500) below a predetermined threshold. The operation method of the multi-beam charged particle microscope (1) according to any one of claims 1 to 4, further comprising calculating the start time of the second time interval Ts2 during the third time interval Tr, so that the second image The positional deviation of the second center position 21.2 of the patch 17.2 from the line of sight (53) of the multiple beam charged particle microscope (1) or the movement speed of the wafer stage (500) is below a predetermined threshold. The operation method of the multi-beam charged particle microscope (1) according to any one of claims 1 to 5, further comprising the following steps: predicting a series of wafer stage positions during the third time interval Tr; calculating at least first and second control signals from the predicted wafer stage position; The first control signal is provided to a first deflection yoke (110) in the primary beam path (13) of the multiple beam charged particle microscope (1), and the second control signal is provided to the multiple beam charged A second deflection system (222) in the secondary beam path (11) of the particle microscope (1). A high-throughput and high-resolution multiple beam charged particle system (1) comprising a charged particle multiple beamlet generator (300) for generating a plurality of primary charged particle beamlets (3); An object irradiation unit (100) comprising a first deflection system (110) for scanning a wafer surface (25) arranged in an object plane (101) with a plurality of primary charged particle beamlets (3) for scanning with a plurality of primary charged particle beamlets (3) generating a plurality of secondary electron beamlets (9) emitted from the wafer surface (25) at spot positions (5) of a plurality of primary charged particle beamlets (3); A detection unit (200) having a projection system (205), a second deflection system (222) and an image sensor (207) for imaging a plurality of secondary electron beamlets (9) on on an image sensor (207) and during use to capture digital images of a first image patch (17.1) and a second image patch (17.2) of the wafer surface (25); A wafer stage (500) including a stage motion controller, wherein the stage motion controller includes a plurality of motors configured to be independently controlled, the stage configured for capturing the first image patch (17.1) and during digital imaging of the second image patch (17.2), positioning and maintaining the wafer surface (25) within the object plane (101); a plurality of detectors including the stage position sensor (520) and the image sensor (207), the detectors configured to generate a plurality of sensor data during use, the sensor The data includes the position data of the wafer stage (500); A control unit (800) configured to perform, during use, a first image capture of a first image patch 17.1 in a first time interval Ts1 and a second image in a second time interval Ts2 second image capture of patch 17.2 and configured to trigger the wafer stage (500) during a third time interval Tr to remove the wafer stage (500) from the first image of the patch (17.1) The center position (21.1) is moved to the second center position (21.2) of the second image patch 17.2, so that at least one of the first time interval Ts1 and the second time interval Ts2 and the third time interval Tr have a overlapping. The system of claim 7, wherein the control unit is further configured to determine the start time of the third time interval Tr during the first time interval Ts1 such that the first center position of the first image patch 17.1 is the same as the The positional deviation of the sight line (53) of the multiple beam charged particle microscope (1) or the moving speed of the wafer stage (500) is lower than a predetermined threshold. The system of claim 7 or 8, wherein the control unit is further configured to determine the start time of the second time interval Ts2 during the third time interval Tr such that the second center position of the second image patch 17.2 21.2 The positional deviation from the line of sight (53) of the multiple beam charged particle microscope (1) or the moving speed of the wafer stage (500) is below a predetermined threshold. The system of any one of claims 7 to 9, wherein the control unit is further configured for predicting a series of wafer stage positions during the third time interval Tr, and for calculating from the predicted wafer stage positions at least first and second control signals, and for providing the first control signal to the first deflection yoke (110) in the primary beam path (13) and the second control signal to the multiple beams A second deflection yoke (222) in the secondary beam path (11) of the charged particle microscope (1). A method of operation of a multiple beam charged particle system (1) with high flux and high resolution, comprising: A first image capture of a first image patch 17.1, a second image capture of a second image patch 17.2 and the wafer stage (500) from the first center of the first image patch (17.1) The position (21.1) is moved to the second center position (21.2) of the second image patch 17.2, all within a time interval TG in The first image capture of the first image patch 17.1 is during the first time interval Ts1; The second image capture of the second image patch 17.2 is during the second time interval Ts2; and During the third time interval Tr, the wafer stage (500) is moved from a first center position (21.1) of the first image patch (17.1) to a second center position (21.1) of the second image patch 17.2 ( 21.2); and where The time interval TG is less than the sum of Ts1, Ts2 and Tr: TG < Ts1 + Ts2 + Tr. A multiple beam charged particle microscope (1) for wafer inspection, comprising: a charged particle multiple beamlet generator (300) for generating a plurality of primary charged particle beamlets (3); An object irradiation unit (100) comprising a first deflection system (110) for scanning a wafer surface (25) arranged in an object plane (101) with a plurality of primary charged particle beamlets (3) for scanning with a plurality of primary charged particle beamlets (3) generating a plurality of secondary electron beamlets (9) emitted from the wafer surface (25) at the scanning spot position (5) of the plurality of primary charged particle beamlets (3); A detection unit (200) having a projection system (205), a second deflection system (222) and an image sensor (207) for imaging a plurality of secondary electron beamlets (9) on on an image sensor (207) and during use to capture digital images of a first image patch (17.1) and a second image patch (17.2) of the wafer surface (25); Wafer stage (500) with stage position sensor (520) for positioning and maintaining the wafer surface (25) in the object during acquisition of digital images of the first image patch (17.1) in plane (101) and for moving the wafer surface from the first image patch (17.1) to the second image patch (17.2); a plurality of detectors including the stage position sensor (520) and the image sensor (207), the detectors configured to generate a plurality of sensor data during use, the sensor The data includes the position data of the wafer stage (500); The first compensator in the object irradiation unit (100) is configured to move or rotate the scanning spot positions (5) of the plurality of primary charged particle beamlets (3) on the wafer surface (25), A second compensator in the projection system (205) configured to compensate for displacement or rotation of the scanning spot positions (5) of the plurality of primary charged particle beamlets (3) and maintain the image detector ( The spot positions (15) of the plurality of secondary electron beamlets (9) on 207) are constant; A control unit (800) is configured to generate a first set of control signals Cp from a plurality of sensor data for capturing digital images of the first image patch (17.1) or the second image patch (17.2) During this period, a first compensator in the object irradiation unit (100) and a second compensator in the projection system (205) are controlled synchronously. The multiple beam charged particle microscope (1) of claim 12, wherein the control _unit ( ₈₀₀ ) is configured to provide the first and The second compensator is used to compensate the position change or orientation change of the wafer stage (500). The multiple-beam charged particle microscope (1) of any one of claims 12 or 13, wherein the control unit (800) is configured by calculating the first set of control signals _Cp and converting the first set of control signals _Cp The first and second compensators are provided to compensate for positional variations of the line of sight (53) of the object illumination unit (100). The multiple beam charged particle microscope (1) of any one of claims 12 to 14, wherein the control unit (800) is configured by calculating the first set of control signals _Cp and converting the first set of control signals _Cp The first and second compensators are provided for compensating for positional changes or orientation changes of the wafer stage (500) and positional changes of the line of sight (53) of the object irradiation unit (100). The multiple beam charged particle microscope ( 1 ) of any one of claims 12 to 15, wherein the control unit ( 800 ) is configured by calculating the first set of control signals C _p and converting the first set of control signals C _p provided to the first and the second compensator to compensate for the speed of movement of the wafer stage (500) during the capture of the digital image of the first image patch (17.1) or the second image patch (17.2) . A method of inspecting wafers using a multiple beam charged particle microscope, the steps are as follows: a first image capturing step of the first image patch during a first time interval Ts1; movement of the wafer stage from the position of the first image patch to the second image patch during a time interval Tr; and a second image capturing step of the second image patch during a second time interval Ts2, whereby, During the first time interval Ts1 at least a first error amplitude is calculated from the plurality of sensor signals, During the first time interval Ts1, the predicted first error amplitude develops at least through the time interval Tr and the second time interval Ts2; And, at least during this time interval Tr, a control signal is provided to the control unit of the multiple beam charged particle microscope for keeping the predicted development of the error amplitude during this second time interval Ts2 below a predetermined threshold. The method of claim 17, wherein the prediction of the development of the first error amplitude is generated according to a prediction model or extrapolation. The method of claim 17 or 18, wherein the first error amplitude represents at least one of line-of-sight displacement, wafer stage displacement, wafer stage rotation, line-of-sight rotation, magnification error, focus error, astigmatism error, or distortion error. 19. The method of any one of claims 17 to 19, wherein the control signal is provided to a control unit of the multiple beam charged particle microscope for controlling a wafer stage, a first deflection unit, a second deflection unit, and multiple beamlets A component of at least one of the fast compensator of the generation unit or the fast compensator of the detection unit. A method of operating a multiple beam charged particle microscope with a control unit, the method comprising a series of operating steps during image acquisition of a series of image patches including a first image patch and a second subsequent image patch, which include: expanding the data stream forming the plurality of sensor data into a set of error amplitudes; capture a set of drift control signals and a set of dynamic control signals, and providing the set of drift control signals to the slow acting compensator; and The set of drift control signals are provided to the fast acting compensator. The method of claim 21, wherein the step of capturing the set of drift control signals and the set of dynamic control signals is performed during a first time interval Ts1 of image capturing of the first image patch; and the set of drift control signals is controlled The step of providing the signal to the slow acting compensator is performed during the time interval Tr during which the substrate is moved by using the substrate stage from the first image patch to the second image patch. A method as claimed in claim 21 or 22, wherein the step of providing the set of dynamic control signals to the fast motion compensator is performed within the first time interval Ts1. The method of claim 22 or 23, wherein the step of providing the set of dynamic control signals to the fast motion compensator is further performed within the image scanning time interval Ts2 of the second image patch. The method of any one of claims 21 to 24, further comprising the step of predicting the temporal development of at least one error amplitude. The method of claim 25, comprising predicting at least one slowly varying drift in error amplitude and predicting at least one rapidly varying dynamic change in error amplitude. A non-transitory computer-readable medium including a set of instructions executable by one or more processors of a device to cause the device to perform a method, wherein the device includes a source of charged particles to generate a plurality of primary charged particle electron beams, and the method includes: determining the lateral displacement of the stage, wherein the stage is movable in at least one of the X-Y axes; determining the lateral displacement of the line of sight of an object illuminating unit; and The controller is instructed to apply a first signal to deflect the plurality of primary charged particle beamlets incident on the sample to at least partially compensate for the lateral displacement.

Images